| 1. |
- Na Zhao, Li, et al.
(författare)
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Cascading proton transfers are a hallmark of the catalytic mechanism of SAM-dependent methyltransferases
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 594:13, s. 2128-2139
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Tidskriftsartikel (refereegranskat)abstract
- The S-adenosyl-L-methionine (SAM)-dependent methyltransferases attach a methyl group to the deprotonated methyl lysine (Kme0) using SAM as a donor. An intriguing, yet unanswered, question is how the deprotonation of the methyl lysine takes place which results in a lone pair of electrons at the Nϵ atom of the methyl lysine for the following methyl transfer. PRDM9, one of the few methyltransferases with well-defined enzyme activity in vitro and in vivo, is a good representative of the PR/SET domain methyltransferase family to study the deprotonation and subsequently the methyl transfer. The reaction consists of two progressing steps: (i) the absolutely required substrate methyl lysine deprotonation and (ii) the transfer of the methyl group to the deprontonated methyl lysine. We use empirical valence bond (EVB) simulations to evaluate Y357 at the active site as potential general base for the deprotonation of the methyl lysine. Indeed, our study has found that the pKa of Tyr357 is low enough to make it an ideal candidate for proton abstraction from the methyl lysine. The partially deprontonated Tyr357 is able to change its H-bond pattern thus bridging two proton tunneling states (OH- H 0-Tyr357 and Kme0-Nϵ H O-Tyr357) and providing a cascading proton transfer from Tyr357 to hydroxide, generating deprotonated Tyr357 and then from Kme0 to the deprotonated Tyr357 resulting in deprotonated methyl lysine. This cascading proton transfer shortens the lifespan of the labile intermediates, and affects the conformational changes during the product release important to promote the proton release to the bulk solvent. Our computational efforts have uncovered a new catalytic mechanism to unravel the unanswered question about the deprotonation of the methyl lysine in methyltransferases.
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| 2. |
- Riesbeck, Kristian
(författare)
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Complement evasion by the human respiratory tract pathogens Haemophilus influenzae and Moraxella catarrhalis
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:16, s. 2586-2597
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Forskningsöversikt (refereegranskat)abstract
- All infective bacterial species need to conquer the innate immune system in order to colonize and survive in their hosts. The human respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis are no exceptions and have developed sophisticated mechanisms to evade complement-mediated killing. Both bacterial species carry lipooligosaccharides preventing complement attacks and attract and utilize host complement regulators C4b binding protein and factor H to inhibit the classical and alternative pathways of complement activation, respectively. In addition, the regulator of the terminal pathway of complement activation, vitronectin, is hijacked by both bacteria. An array of different outer membrane proteins (OMP) in H. influenzae and M. catarrhalis simultaneously binds complement regulators, but also plasminogen. Several of the bacterial complement-binding proteins are important adhesins and contain highly conserved regions for interactions with the host. Thus, some of the OMP are viable targets for new therapeutics, including vaccines aimed at preventing respiratory tract diseases such as otitis media in children and exacerbations in patients suffering from chronic obstructive pulmonary disease.
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| 3. |
- Kelley, Liam P., et al.
(författare)
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Dimerization of small integral membrane protein 1 promotes cell surface presentation of the Vel blood group epitope
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:8, s. 1261-1270
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Tidskriftsartikel (refereegranskat)abstract
- The Vel blood group antigen is carried on the short extracellular segment of the 78-amino-acid-long, type II transmembrane protein SMIM1 of unknown function. Here, using biochemical analysis and flow cytometry of cells expressing wild-type and mutant alleles of SMIM1, we demonstrate that dimerization of SMIM1 promotes cell surface display of the Vel epitope. We show that SMIM1 dimerization is mediated both by an extracellular Cys77-dependent, homomeric disulfide linkage and via a GxxxG helix–helix interaction motif in the transmembrane domain. These results provide important context for the observed variability in reactivity patterns of clinically important anti-Vel identified in patient sera.
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| 4. |
- Škerlová, Jana, et al.
(författare)
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Structure and steroid isomerase activity of Drosophila glutathione transferase E14 essential for ecdysteroid biosynthesis
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:7, s. 1187-1195
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Tidskriftsartikel (refereegranskat)abstract
- Ecdysteroids are critically important for the formation of the insect exoskeleton. Cholesterol is a precursor of ecdysone and its active form 20-hydroxyecdysone, but some steps in the ecdysteroid biosynthesis pathway remain unknown. An essential requirement of glutathione (GSH) transferase GSTE14 in ecdysteroid biosynthesis has been established in Drosophila melanogaster, but its function is entirely unknown. Here, we have determined the crystal structure of GSTE14 in complex with GSH and investigated the kinetic properties of GSTE14 with alternative substrates. GSTE14 has high-ranking steroid double-bond isomerase activity, albeit 50-fold lower than the most efficient mammalian GSTs. Corresponding steroid isomerizations are unknown in insects, and their exact physiological role remains to be shown. Nonetheless, the essential enzyme GSTE14 is here demonstrated to be catalytically competent and have a steroid-binding site.
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| 5. |
- Kumar, Pravin, et al.
(författare)
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Clinically observed deletions in SARS-CoV-2 Nsp1 affect its stability and ability to inhibit translation
- 2022
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 596:9, s. 1203-1213
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Tidskriftsartikel (refereegranskat)abstract
- Nonstructural protein 1 (Nsp1) of SARS-CoV-2 inhibits host cell translation through an interaction between its C-terminal domain and the 40S ribosome. The N-terminal domain (NTD) of Nsp1 is a target of recurring deletions, some of which are associated with altered COVID-19 disease progression. Here, we characterize the efficiency of translational inhibition by clinically observed Nsp1 deletion variants. We show that a frequent deletion of residues 79–89 severely reduces the ability of Nsp1 to inhibit translation while not abrogating Nsp1 binding to the 40S. Notably, while the SARS-CoV-2 5′ untranslated region enhances translation of mRNA, it does not protect from Nsp1-mediated inhibition. Finally, thermal stability measurements and structure predictions reveal a correlation between stability of the NTD and the efficiency of translation inhibition.
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| 6. |
- Petrlova, Jitka, et al.
(författare)
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SARS-CoV-2 spike protein aggregation is triggered by bacterial lipopolysaccharide
- 2022
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 596:19, s. 2566-2575
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Tidskriftsartikel (refereegranskat)abstract
- SARS-CoV-2 spike (S) protein is crucial for virus invasion in COVID-19. Here, we showed that lipopolysaccharide (LPS) can trigger S protein aggregation at high doses of LPS and S protein. We demonstrated the formation of S protein aggregates by microscopy analyses, aggregation and gel shift assays. LPS at high levels boosts the formation of S protein aggregates as detected by amytracker and thioflavin T dyes that specifically bind to aggregating proteins. We validated the role of LPS by blocking the formation of aggregates by the endotoxin-scavenging thrombin-derived peptide TCP-25. Aggregation-prone sequences in S protein are predicted to be nearby LPS binding sites, while molecular simulations showed stable formation of S protein–LPS higher-order oligomers. Collectively, our results provide evidence of LPS-induced S protein aggregation.
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| 7. |
- Uzuncayir, Sibel, et al.
(författare)
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Analyses of the complex formation of staphylococcal enterotoxin A and the human gp130 cytokine receptor
- 2022
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 596:7, s. 910-923
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Tidskriftsartikel (refereegranskat)abstract
- Superantigens (SAgs) are bacterial enterotoxins produced by Staphylococcus aureus. Staphylococcal enterotoxin type A (SEA), a staphylococcal superantigen, has been shown to bind to the cytokine signalling receptor glycoprotein 130 (gp130). The structural details, as well as the exact physiological role of this interaction, remain unclear. Here, we describe the structural details of the SEA–gp130 complex by combining crosslinking mass spectrometry and computational modelling. Interestingly, SEA is not able to bind gp130-homologues from rat and mouse. Our data suggest that SEA may interact with human gp130 in a different manner than other known gp130-ligands. Moreover, the fact that SEA does not bind mouse or rat gp130 suggests that SAgs have additional mechanisms of action in humans.
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| 8. |
- Diamanti, Riccardo, et al.
(författare)
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Comparative structural analysis provides new insights into the function of R2-like ligand-binding oxidase
- 2022
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 596:12, s. 1600-1610
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Tidskriftsartikel (refereegranskat)abstract
- R2-like ligand-binding oxidase (R2lox) is a ferritin-like protein that harbours a heterodinuclear manganese–iron active site. Although R2lox function is yet to be established, the enzyme binds a fatty acid ligand coordinating the metal centre and catalyses the formation of a tyrosine–valine ether cross-link in the protein scaffold upon O2 activation. Here, we characterized the ligands copurified with R2lox by mass spectrometry-based metabolomics. Moreover, we present the crystal structures of two new homologs of R2lox, from Saccharopolyspora erythraea and Sulfolobus acidocaldarius, at 1.38 Å and 2.26 Å resolution, respectively, providing the highest resolution structure for R2lox, as well as new insights into putative mechanisms regulating the function of the enzyme.
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| 9. |
- Encarnacao, Joao Crispim, Master, 1990-, et al.
(författare)
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A real-time cell-binding assay reveals dynamic features of STxB-Gb3 cointernalization and STxB-mediated cargo delivery into cancer cells
- 2020
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Ingår i: FEBS Letters. - : WILEY. - 0014-5793 .- 1873-3468. ; 594:15, s. 2406-2420
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between the Shiga toxin B-subunit (STxB) and its globotriaosylceramide receptor (Gb3) has a high potential for being exploited for targeted cancer therapy. The primary goal of this study was to evaluate the capacity of STxB to carry small molecules and proteins as cargo into cells. For this purpose, an assay was designed to provide real-time information about the StxB-Gb3 interaction as well as the dynamics and mechanism of the internalization process. The assay revealed the ability to distinguish the process of binding to the cell surface from internalization and presented the importance of receptor and STxB clustering for internalization. The overall setup demonstrated that the binding mechanism is complex, and the concept of affinity is difficult to apply. Hence, time-resolved methods, providing detailed information about the interaction of STxB with cells, are critical for the optimization of intracellular delivery.
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| 10. |
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| 11. |
- Nicolaus, Felix, et al.
(författare)
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Upstream charged and hydrophobic residues impact the timing of membrane insertion of transmembrane helices
- 2022
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 596:8, s. 1004-1012
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Tidskriftsartikel (refereegranskat)abstract
- During SecYEG-mediated cotranslational insertion of membrane proteins, transmembrane helices (TMHs) first make contact with the membrane when their N-terminal end is ~ 45 residues away from the peptidyl transferase centre. However, we recently uncovered instances where the first contact is delayed by up to ~ 10 residues. Here, we recapitulate these effects using a model TMH fused to two short segments from the Escherichia coli inner membrane protein BtuC: a positively charged loop and a re-entrant loop. We show that the critical residues are two Arg residues in the positively charged loop and four hydrophobic residues in the re-entrant loop. Thus, both electrostatic and hydrophobic interactions involving sequence elements that are not part of a TMH can impact the way the latter behaves during membrane insertion.
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| 12. |
- Raji, Olanrewaju, et al.
(författare)
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The coordinated action of glucuronoyl esterase and α-glucuronidase promotes the disassembly of lignin–carbohydrate complexes
- 2021
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 595:3, s. 351-359
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Tidskriftsartikel (refereegranskat)abstract
- Glucuronoxylans represent a significant fraction of woody biomass, and its decomposition is complicated by the presence of lignin–carbohydrate complexes (LCCs). Herein, LCCs from birchwood were used to investigate the potential coordinated action of a glucuronoyl esterase (TtCE15A) and two α-glucuronidases (SdeAgu115A and AxyAgu115A). When supplementing α-glucuronidase with equimolar quantities of TtCE15A, total MeGlcpA released after 72 h by SdeAgu115A and AxyAgu115A increased from 52% to 67%, and 61% to 95%, respectively. Based on the combined TtCE15A and AxyAgu115A activities, ~ 34% of MeGlcpA in the extracted birchwood glucuronoxylan was occupied as LCCs. Notably, insoluble LCC fractions reduced soluble α-glucuronidase concentrations by up to 70%, whereas reduction in soluble TtCE15A was less than 30%, indicating different tendencies to adsorb onto the LCC substrate.
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| 13. |
- Bonne Kohler, Julie, et al.
(författare)
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Importance of protein Ser/Thr/Tyr phosphorylation for bacterial pathogenesis
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 594:15, s. 2339-2369
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Forskningsöversikt (refereegranskat)abstract
- Protein phosphorylation regulates a large variety of biological processes in all living cells. In pathogenic bacteria, the study of serine, threonine, and tyrosine (Ser/Thr/Tyr) phosphorylation has shed light on the course of infectious diseases, from adherence to host cells to pathogen virulence, replication, and persistence. Mass spectrometry (MS)-based phosphoproteomics has provided global maps of Ser/Thr/Tyr phosphosites in bacterial pathogens. Despite recent developments, a quantitative and dynamic view of phosphorylation events that occur during bacterial pathogenesis is currently lacking. Temporal, spatial, and subpopulation resolution of phosphorylation data is required to identify key regulatory nodes underlying bacterial pathogenesis. Herein, we discuss how technological improvements in sample handling, MS instrumentation, data processing, and machine learning should improve bacterial phosphoproteomic datasets and the information extracted from them. Such information is expected to significantly extend the current knowledge of Ser/Thr/Tyr phosphorylation in pathogenic bacteria and should ultimately contribute to the design of novel strategies to combat bacterial infections.
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| 14. |
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| 15. |
- Lee, Seoeun, et al.
(författare)
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The Mgr2 subunit of the TIM23 complex regulates membrane insertion of marginal stop-transfer signals in the mitochondrial inner membrane
- 2020
-
Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:6, s. 1081-1087
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Tidskriftsartikel (refereegranskat)abstract
- The TIM23 complex mediates membrane insertion of presequence-containing mitochondrial proteins via a stop-transfer mechanism. Stop-transfer signals consist of hydrophobic transmembrane segments and flanking charges. Mgr2 functions as a lateral gatekeeper of the TIM23 complex. However, it remains elusive which features of stop-transfer signals are discriminated by Mgr2. To determine the effects of Mgr2 on the TIM23-mediated stop-transfer pathway, we measured membrane insertion of model transmembrane segments of varied hydrophobicity and flanking charges in Mgr2-deletion or -overexpression yeast strains. We found that upon deletion of Mgr2, the threshold hydrophobicity for membrane insertion, as well as the requirement for matrix-facing positive charges, is reduced. These results imply that the Mgr2-mediated gatekeeper function is important for controlling membrane sorting of marginal stop-transfer signals.
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| 16. |
- Zhao, Hongxing, et al.
(författare)
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Adenovirus in the omics era - a multi-pronged strategy.
- 2020
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:12, s. 1879-1890
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Tidskriftsartikel (refereegranskat)abstract
- Human adenoviruses (HAdVs) are common pathogens associated with a wide variety of respiratory, ocular and gastrointestinal diseases. To achieve its effective lytic mode of replication, HAdVs have to reprogram host-cell gene expression and fine-tune viral gene expression in a temporal manner. In two decades, omics revolution has advanced our knowledge about the HAdV and host cell interplay at the RNA and protein levels. This review summarizes the current knowledge from large-scale datasets how HAdV infections adjust coding and non-coding RNA expression, as well as how they reprogram host-cell proteome during the lytic course of infection.
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| 17. |
- Carlström, Andreas, 1988, et al.
(författare)
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Insights into conformational changes in cytochrome b during the early steps of its maturation
- 2024
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Ingår i: FEBS LETTERS. - 0014-5793 .- 1873-3468. ; 598:11, s. 1438-1448
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Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins carrying redox cofactors are key subunits of respiratory chain complexes, yet the exact path of their folding and maturation remains poorly understood. Here, using cryo-EM and structure prediction via Alphafold2, we generated models of early assembly intermediates of cytochrome b (Cytb), a central subunit of complex III. The predicted structure of the first assembly intermediate suggests how the binding of Cytb to the assembly factor Cbp3-Cbp6 imposes an open configuration to facilitate the acquisition of its heme cofactors. Moreover, structure predictions of the second intermediate indicate how hemes get stabilized by binding of the assembly factor Cbp4, with a concomitant weakening of the contact between Cbp3-Cbp6 and Cytb, preparing for the release of the fully hemylated protein from the assembly factors.
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| 18. |
- Cicirò, Ylenia, et al.
(författare)
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The mitotic checkpoint kinase BUB1 is a direct and actionable target of MYB in adenoid cystic carcinoma
- 2024
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 598:2, s. 252-265
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Tidskriftsartikel (refereegranskat)abstract
- Adenoid cystic carcinoma (ACC) is a head and neck cancer that frequently originates in salivary glands, but can also strike other exocrine glands such as the breast. A key molecular alteration found in the majority of ACC cases is MYB gene rearrangements, leading to activation of the oncogenic transcription factor MYB. In this study, we used immortalised breast epithelial cells and an inducible MYB transgene as a model of ACC. Molecular profiling confirmed that MYB-driven gene expression causes a transition into an ACC-like state. Using this new cell model, we identified BUB1 as a targetable kinase directly controlled by MYB, whose pharmacological inhibition caused MYB-dependent synthetic lethality, growth arrest and apoptosis of patient-derived cells and organoids.
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| 19. |
- Dimarogona, Maria, et al.
(författare)
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The crystal structure of a Fusarium oxysporum feruloyl esterase that belongs to the tannase family
- 2020
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 594:11, s. 1738-1749
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Tidskriftsartikel (refereegranskat)abstract
- Feruloyl esterases are enzymes of industrial interest that catalyse the hydrolysis of the ester bond between hydroxycinnamic acids such as ferulic acid and sugars present in the plant cell wall. Although there are several structures of biochemically characterized feruloyl esterases available, the structural determinants of their substrate specificity are not yet fully understood. Here, we present the crystal structure of a feruloyl esterase from Fusarium oxysporum (FoFaeC) at 2.3 Å resolution. Similar to the two other tannase‐like feruloyl esterases, FoFaeC features a large lid domain covering the active site with potential regulatory role and a disulphide bond that brings together the serine and histidine of the catalytic triad. Differences are mainly observed in the metal coordination site and the substrate binding pocket.
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| 20. |
- Haase, Robert, et al.
(författare)
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A Hitchhiker's guide through the bio‐image analysis software universe
- 2022
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 596:19, s. 2472-2485
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Forskningsöversikt (refereegranskat)abstract
- Modern research in the life sciences is unthinkable without computational methods for extracting, quantifying and visualising information derived from microscopy imaging data of biological samples. In the past decade, we observed a dramatic increase in available software packages for these purposes. As it is increasingly difficult to keep track of the number of available image analysis platforms, tool collections, components and emerging technologies, we provide a conservative overview of software that we use in daily routine and give insights into emerging new tools. We give guidance on which aspects to consider when choosing the platform that best suits the user's needs, including aspects such as image data type, skills of the team, infrastructure and community at the institute and availability of time and budget.
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| 21. |
- Hu, Min, et al.
(författare)
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Overactivation of the androgen receptor exacerbates gravid uterine ferroptosis via interaction with and suppression of the NRF2 defense signaling pathway.
- 2022
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Ingår i: FEBS letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 596:8, s. 806-825
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms through which the androgen-dependent activation of the androgen receptor (AR) regulates graviduterine ferroptosis remain unknown.We show that whileco-exposure of pregnant rats to the androgen 5α-dihydrotestosterone (DHT) and insulin (INS)triggereduterineferroptotic signaling cascades,additional treatment with the anti-androgenflutamide increasedexpression of the key ferroptosis-inhibitory proteins SLC7A11, GSH, and GPX4, reduced iron content, normalized levels offerroptosis-associated Tfrc,Fpn1, andHo1mRNAs, reduced levels of proteins modified by 4-HNE (a marker of ferroptosis), andrestored protein levels of NRF2, a key transcription factor regulating antioxidant defense signaling, in the gravid uterus.Furthermore,exposure to DHT aloneincreaseduterine ferroptosis, and NRF2 abundance was negatively correlated withAR status.Co-immunoprecipitation and Western blot assays revealed that the AR physically interacted with endogenous NRF2, and this interaction was increased by DHT exposurein vivo.Our results suggest that AR overactivation and NRF2 suppression cooperate in the regulation ofNRF2-targets in uterine ferroptosis.
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| 22. |
- Isidor, Marie S., et al.
(författare)
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Pyruvate kinase M2 represses thermogenic gene expression in brown adipocytes
- 2020
-
Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 594:7, s. 1218-1225
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing the thermogenic capacity of brown adipose tissue is a potential anti-obesity strategy; therefore, the mechanisms controlling expression of thermogenesis-related genes are of interest. Pyruvate kinase (PK) catalyzes the last step of glycolysis and exists as four isoenzymes: PK, liver, PK, red blood cell, PK, muscle (PKM1 and PKM2). PKM2 has both glycolytic and nuclear functions. Here, we report that PKM2 is enriched in brown adipose compared with white adipose tissue. Specific knockdown of PKM2 in mature brown adipocytes demonstrates that silencing of PKM2 does not lead to a decrease in PK activity, but causes a robust upregulation of thermogenic uncoupling protein 1 (Ucp1) and fibroblast growth factor 21 (Fgf21) gene expression. This increase is not mediated by any of the known mechanisms for PKM2-regulated gene expression, thus implying the existence of a novel mechanism for PKM2-dependent effects on gene expression.
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| 23. |
- Košenina, Sara, et al.
(författare)
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Crystal structure of the OrfX1–OrfX3 complex from the PMP1 neurotoxin gene cluster
- 2023
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 597:4, s. 515-523
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Tidskriftsartikel (refereegranskat)abstract
- Paraclostridial mosquitocidal protein 1 (PMP1) is a member of the clostridial neurotoxin (CNT) family, which includes botulinum and tetanus neurotoxins. PMP1 has unique selectivity for anopheline mosquitos and is the only known member of the family that targets insects. PMP1 is encoded in an orfX gene cluster, which in addition to the toxin, consists of OrfX1, OrfX2, OrfX3, P47 and NTNH, which have been shown to aid in PMP1 toxicity. We here show that OrfX1 and OrfX3 form a complex and present its structure at 2.7 Å. The OrfX1–OrfX3 complex mimics the structure of full-length OrfX2 and belongs to the lipid-binding TULIP protein superfamily. With this report, the structures of all proteins encoded in the orfX gene cluster of CNTs are now determined.
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| 24. |
- Mazurkewich, Scott, 1982, et al.
(författare)
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A unique AA5 alcohol oxidase fused with a catalytically inactive CE3 domain from the bacterium Burkholderia pseudomallei
- 2023
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Ingår i: FEBS Letters. - 1873-3468 .- 0014-5793. ; 597:13, s. 1779-1791
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Tidskriftsartikel (refereegranskat)abstract
- Copper radical oxidases (CROs) are redox enzymes able to oxidize alcohols or aldehydes, while only requiring a single copper atom as cofactor. Studied CROs are found in one of two subfamilies within the Auxiliary Activities family 5 (AA5) in the carbohydrate-active enzymes database. We here characterize an AA5 enzyme outside the subfamily classification from the opportunistic bacterial pathogen Burkholderia pseudomallei, which curiously was fused to a carbohydrate esterase family 3 domain. The enzyme was shown to be a promiscuous primary alcohol oxidase, with an activity profile similar to enzymes from subfamily 2. The esterase domain was inactive on all tested substrates, and structural predictions revealed this being an effect of crippling substitutions in the expected active site residues.
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| 25. |
- Mermans, Daphne, et al.
(författare)
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Cotranslational folding of human growth hormone in vitro and in Escherichia coli
- 2023
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 597:10, s. 1355-1362
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Tidskriftsartikel (refereegranskat)abstract
- Human growth hormone (hGH) is a four-helix bundle protein of considerable pharmacological interest. Recombinant hGH is produced in bacteria, yet little is known about its folding during expression in Escherichia coli. We have studied the cotranslational folding of hGH using force profile analysis (FPA), both during in vitro translation in the absence and presence of the chaperone trigger factor (TF), and when expressed in E. coli. We find that the main folding transition starts before hGH is completely released from the ribosome, and that it can interact with TF and possibly other chaperones.
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| 26. |
- Ramesh, Rashmi, et al.
(författare)
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Domain II of the translation elongation factor eEF1A is required for Gcn2 kinase inhibition
- 2020
-
Ingår i: FEBS Letters. - : WILEY. - 0014-5793 .- 1873-3468.
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Tidskriftsartikel (refereegranskat)abstract
- The signalling pathway governing general control nonderepressible (Gcn)2 kinase allows cells to cope with amino acid shortage. Under starvation, Gcn2 phosphorylates the translation initiation factor eukaryotic translation initiation factor (eIF)2 alpha, triggering downstream events that ultimately allow cells to cope with starvation. Under nutrient-replete conditions, the translation elongation factor eEF1A binds Gcn2 to contribute to keeping Gcn2 inactive. Here, we aimed to map the regions in eEF1A involved in binding and/or regulating Gcn2. We find that eEF1A amino acids 1-221 and 222-315, containing most of domains I and II, respectively, bind Gcn2 in vitro. Overexpression of eEF1A lacking or containing domain III impairs eIF2 alpha phosphorylation. While the latter reduces growth under starvation similarly to eEF1A lacking domain I, the former enhances growth in a Gcn2-dependent manner. Our studies suggest that domain II is required for Gcn2 inhibition and that eEF1A lacking domain III mainly affects the Gcn2 response pathway downstream of Gcn2.
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| 27. |
- Sahu, Welka, et al.
(författare)
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Plasmodium falciparum HSP40 protein eCiJp traffics to the erythrocyte cytoskeleton and interacts with the human HSP70 chaperone HSPA1
- 2022
-
Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 596:1, s. 95-111
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Tidskriftsartikel (refereegranskat)abstract
- Renovation of host erythrocytes is vital for pathogenesis by Plasmodium falciparum. These changes are mediated by parasite proteins that translocate beyond the parasitophorous vacuolar membrane in an unfolded state, suggesting protein folding by chaperones is imperative for the functionality of exported proteins. We report a type IV P. falciparum heat-shock protein 40, PF11_0034, that localizes to the cytoplasmic side of J-dots and interacts with the erythrocyte cytoskeleton, and therefore named eCiJp (erythrocyte cytoskeleton-interacting J protein). Recombinant eCiJp binds to the human heat-shock protein 70 HsHSPA1 and promotes its ATPase activity. In addition, eCiJp could suppress protein aggregation. Our data suggest that eCiJp recruits HsHSPA1 to the host erythrocyte cytoskeleton, where it may become involved in remodeling of the erythrocyte cytoskeleton and/or folding of exported parasite proteins.
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| 28. |
- Siegbahn, Per E. M., 1945-
(författare)
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Computational modeling of redox enzymes
- 2023
-
Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 597:1, s. 38-44
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Forskningsöversikt (refereegranskat)abstract
- A computational methodology is briefly described, which appears to be able to accurately describe the mechanisms of redox active enzymes. The method is built on hybrid density functional theory where the inclusion of a fraction of exact exchange is critical. Two examples of where the methodology has been applied are described. The first example is the mechanism for water oxidation in photosystem II, and the second one is the mechanism for N2 activation by nitrogenase. The mechanism for PSII has obtained very strong support from subsequent experiments. For nitrogenase, the calculations suggest that there should be an activation process prior to catalysis, which is still strongly debated.
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| 29. |
- Simon, Philipp S., et al.
(författare)
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Capturing the sequence of events during the water oxidation reaction in photosynthesis using XFELs
- 2023
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Ingår i: FEBS Letters. - : John Wiley & Sons. - 0014-5793 .- 1873-3468. ; 597:1, s. 30-37
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Tidskriftsartikel (refereegranskat)abstract
- Ever since the discovery that Mn was required for oxygen evolution in plants by Pirson in 1937 and the period-four oscillation in flash-induced oxygen evolution by Joliot and Kok in the 1970s, understanding of this process has advanced enormously using state-of-the-art methods. The most recent in this series of innovative techniques was the introduction of X-ray free-electron lasers (XFELs) a decade ago, which led to another quantum leap in the understanding in this field, by enabling operando X-ray structural and X-ray spectroscopy studies at room temperature. This review summarizes the current understanding of the structure of Photosystem II (PS II) and its catalytic centre, the Mn4CaO5 complex, in the intermediate Si (i = 0–4)-states of the Kok cycle, obtained using XFELs.
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| 30. |
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| 31. |
- Yadav, K., et al.
(författare)
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Phenylalanine stacking enhances the red fluorescence of biliverdin IX alpha on UV excitation in sandercyanin fluorescent protein
- 2022
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Ingår i: Febs Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 596:6, s. 796-805
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Tidskriftsartikel (refereegranskat)abstract
- Biliverdin IX alpha (BV) binds to several prokaryotic and eukaryotic proteins. How nature exploits the versatility of BV's properties is not fully understood. Unlike free BV, the Sandercyanin fluorescent protein bound to BV (SFP-BV) shows enhanced red fluorescence (675 nm) on excitation in the UV region (380 nm). Site-directed mutagenesis showed that the BV complex of two SFP variants, F55A and E79A, resulted in the loss of red fluorescence. Crystal structures of the complexes of these proteins with BV show the absence of stacking interactions of the F55 phenyl ring with BV. BV changes from ZZZssa conformation in the wild-type to ZZZsss conformation in the variants. In the nonfluorescent mutants, the lowest excited state is destabilized, resulting in nonradiative decay.
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| 32. |
- Rodrigues, Joana Isabel, et al.
(författare)
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Yeast chaperones and ubiquitin ligases contribute to proteostasis during arsenite stress by preventing or clearing protein aggregates
- 2023
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Ingår i: Febs Letters. - 0014-5793. ; 597:13, s. 1733-47
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Tidskriftsartikel (refereegranskat)abstract
- Arsenite causes proteotoxicity by targeting nascent proteins for misfolding and aggregation. Here, we assessed how selected yeast chaperones and ubiquitin ligases contribute to proteostasis during arsenite stress. Loss of the ribosome-associated chaperones Zuo1, Ssz1, and Ssb1/Ssb2 reduced global translation and protein aggregation, and increased arsenite resistance. Loss of cytosolic GimC/prefoldin function led to defective aggregate clearance and arsenite sensitivity. Arsenite did not induce ribosomal stalling or impair ribosome quality control, and ribosome-associated ubiquitin ligases contributed little to proteostasis. Instead, the cytosolic ubiquitin ligase Rsp5 was important for aggregate clearance and resistance. Our study suggests that damage prevention, by decreased aggregate formation, and damage elimination, by enhanced aggregate clearance, are important protective mechanisms that maintain proteostasis during arsenite stress.
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| 33. |
- Wahlström, Maria, et al.
(författare)
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MediYoga as a part of a self-management programme among patients with paroxysmal atrial fibrillation - a randomised study
- 2020
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Ingår i: European Journal of Cardiovascular Nursing. - : Oxford University Press (OUP). - 1474-5151 .- 1873-1953. ; 19:1, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Paroxysmal atrial fibrillation is associated with impaired health-related quality of life. Yoga has been suggested to improve health-related quality of life among patients with heart failure and hypertension.AIM: The aim of the study was to evaluate the effects of MediYoga, in respect of health-related quality of life, blood pressure, heart rate, as well as N-terminal pro b-type natriuretic peptide, among patients with symptomatic paroxysmal atrial fibrillation, compared with standard therapy or relaxation.METHODS: Patients with symptomatic paroxysmal atrial fibrillation, n=132, were stratified for gender and randomised to MediYoga, a relaxation group or a control group, 44 patients per group with a 12-week follow-up. Health-related quality of life, blood pressure, heart rate and N-terminal pro b-type natriuretic peptide were assessed.RESULTS: After 12 weeks, there were no differences in health-related quality of life between the groups. There were improvements in Short-Form Health Survey bodily pain, general health, social function, mental health and mental component summary scores within the MediYoga group (p=0.014, p=0.037, p=0.029, p=0.030, p=0.019, respectively). No change was seen in the relaxation and control groups. Systolic blood pressure decreased in the MediYoga group (134±18 to 127±13) compared with the control group (126±17 to 127±15, p=0.041); no difference compared with the relaxation group (131±17 to 125±12). Diastolic blood pressure decreased in the MediYoga group (79±9 to 74 ±9) compared with the control group (76±9 to 79±8, p=0.005); no difference compared with the relaxation group (76±9 to 77±8). There were no differences in heart rate and N-terminal pro b-type natriuretic peptide between the groups after 12 weeks.CONCLUSIONS: MediYoga improves health-related quality of life and decreases blood pressure in patients with paroxysmal atrial fibrillation. MediYoga may be used as a part of a self-management programme among patients with paroxysmal atrial fibrillation.
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