| 11. |
- Knyazeva, Anastasia, 1995-, et al.
(författare)
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A chemical inhibitor of IST1-CHMP1B interaction impairs endosomal recycling and induces noncanonical LC3 lipidation
- 2024
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 121:17
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Tidskriftsartikel (refereegranskat)abstract
- The endosomal sorting complex required for transport (ESCRT) machinery constitutes multisubunit protein complexes that play an essential role in membrane remodeling and trafficking. ESCRTs regulate a wide array of cellular processes, including cytokinetic abscission, cargo sorting into multivesicular bodies (MVBs), membrane repair, and autophagy. Given the versatile functionality of ESCRTs, and the intricate organizational structure of the ESCRT machinery, the targeted modulation of distinct ESCRT complexes is considerably challenging. This study presents a pseudonatural product targeting IST1-CHMP1B within the ESCRT-III complexes. The compound specifically disrupts the interaction between IST1 and CHMP1B, thereby inhibiting the formation of IST1-CHMP1B copolymers essential for normal-topology membrane scission events. While the compound has no impact on cytokinesis, MVB sorting, or biogenesis of extracellular vesicles, it rapidly inhibits transferrin receptor recycling in cells, resulting in the accumulation of transferrin in stalled sorting endosomes. Stalled endosomes become decorated by lipidated LC3, suggesting a link between noncanonical LC3 lipidation and inhibition of the IST1-CHMP1B complex.
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| 12. |
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| 13. |
- Kohler, S, et al.
(författare)
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Binding of vitronectin and Factor H to Hic contributes to immune evasion of Streptococcus pneumoniae serotype 3.
- 2015
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 113:1, s. 125-142
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae serotype 3 strains are highly resistant to opsonophagocytosis due to recruitment of the complement inhibitor Factor H via Hic, a member of the pneumococcal surface protein C (PspC) family. In this study, we demonstrated that Hic also interacts with vitronectin, a fluid-phase regulator involved in haemostasis, angiogenesis, and the terminal complement cascade as well as a component of the extracellular matrix. Blocking of Hic by specific antiserum or genetic deletion significantly reduced pneumococcal binding to soluble and immobilised vitronectin and to Factor H, respectively. In parallel, ectopic expression of Hic on the surface of Lactococcus lactis conferred binding to soluble and immobilised vitronectin as well as Factor H. Molecular analyses with truncated Hic fragments narrowed down the vitronectin-binding site to the central core of Hic (aa 151-201). This vitronectin-binding region is separate from that of Factor H, which binds to the N-terminus of Hic (aa 38-92). Binding of pneumococcal Hic was localised to the C-terminal heparin-binding domain (HBD3) of vitronectin. However, an N-terminal region to HBD3 was further involved in Hic-binding to immobilised vitronectin. Finally, vitronectin bound to Hic was functionally active and inhibited formation of the terminal complement complex. In conclusion, Hic interacts with vitronectin and simultaneously with Factor H, and both human proteins may contribute to colonisation and invasive disease caused by serotype 3 pneumococci.
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| 14. |
- Liu, Guanghui, et al.
(författare)
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Moraxella catarrhalis Evades Host Innate Immunity via Targeting Cartilage Oligomeric Matrix Protein.
- 2016
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 196:3, s. 1249-1258
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella catarrhalis is a respiratory tract pathogen commonly causing otitis media in children and acute exacerbations in patients suffering from chronic obstructive pulmonary disease. Cartilage oligomeric matrix protein (COMP) functions as a structural component in cartilage, as well as a regulator of complement activity. Importantly, COMP is detected in resident macrophages and monocytes, alveolar fluid, and the endothelium of blood vessels in lung tissue. We show that the majority of clinical isolates of M. catarrhalis (n = 49), but not other tested bacterial pathogens, bind large amounts of COMP. COMP interacts directly with the ubiquitous surface protein A2 of M. catarrhalis. Binding of COMP correlates with survival of M. catarrhalis in human serum by inhibiting bactericidal activity of the complement membrane attack complex. Moreover, COMP inhibits phagocytic killing of M. catarrhalis by human neutrophils. We further observed that COMP reduces bacterial adhesion and uptake by human lung epithelial cells, thus protecting M. catarrhalis from intracellular killing by epithelial cells. Taken together, our findings uncover a novel mechanism that M. catarrhalis uses to evade host innate immunity.
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| 15. |
- Liu, Guanghui, et al.
(författare)
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PRELP enhances host innate immunity against the respiratory tract pathogen moraxella catarrhalis
- 2017
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 198:6, s. 2330-2340
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Tidskriftsartikel (refereegranskat)abstract
- Respiratory tract infections are one of the leading causes of mortality worldwide urging better understanding of interactions between pathogens causing these infections and the host. Here we report that an extracellular matrix component proline/arginine-rich end leucine-rich repeat protein (PRELP) is a novel antibacterial component of innate immunity.We detected the presence of PRELP in human bronchoalveolar lavage fluid and showed that PRELP can be found in alveolar fluid, resident macrophages/monocytes, myofibroblasts, and the adventitia of blood vessels in lung tissue. PRELP specifically binds respiratory tract pathogens Moraxella catarrhalis, Haemophilus influenzae, and Streptococcus pneumoniae, but not other bacterial pathogens tested. We focused our study on M. catarrhalis and found that PRELP binds the majority of clinical isolates of M. catarrhalis (n = 49) through interaction with the ubiquitous surface protein A2/A2H. M. catarrhalis usually resists complement-mediated serum killing by recruiting to its surface a complement inhibitor C4b-binding protein, which is also a ligand for PRELP. We found that PRELP competitively inhibits binding of C4b-binding protein to bacteria, which enhances membrane attack complex formation on M. catarrhalis and thus leads to increased serum sensitivity. Furthermore, PRELP enhances phagocytic killing of serum-opsonized M. catarrhalis by human neutrophils in vitro. Moreover, PRELP reduces Moraxella adherence to and invasion of human lung epithelial A549 cells. Taken together, PRELP enhances host innate immunity against M. catarrhalis through increasing complement-mediated attack, improving phagocytic killing activity of neutrophils, and preventing bacterial adherence to lung epithelial cells.
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| 16. |
- Mühlenkamp, Melanie C., et al.
(författare)
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Vitronectin Binds to a Specific Stretch within the Head Region of Yersinia Adhesin A and Thereby Modulates Yersinia enterocolitica Host Interaction
- 2017
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 9:1, s. 33-51
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Tidskriftsartikel (refereegranskat)abstract
- Complement resistance is an important virulence trait of Yersinia enterocolitica (Ye). The predominant virulence factor expressed by Ye is Yersinia adhesin A (YadA), which enables bacterial attachment to host cells and extracellular matrix and additionally allows the acquisition of soluble serum factors. The serum glycoprotein vitronectin (Vn) acts as an inhibitory regulator of the terminal complement complex by inhibiting the lytic pore formation. Here, we show YadA-mediated direct interaction of Ye with Vn and investigated the role of this Vn binding during mouse infection in vivo. Using different Yersinia strains, we identified a short stretch in the YadA head domain of Ye O:9 E40, similar to the ‘uptake region' of Y. pseudotuberculosis YPIII YadA, as crucial for efficient Vn binding. Using recombinant fragments of Vn, we found the C-terminal part of Vn, including heparin-binding domain 3, to be responsible for binding to YadA. Moreover, we found that Vn bound to the bacterial surface is still functionally active and thus inhibits C5b-9 formation. In a mouse infection model, we demonstrate that Vn reduces complement-mediated killing of Ye O:9 E40 and, thus, improved bacterial survival. Taken together, these findings show that YadA-mediated Vn binding influences Ye pathogenesis.
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| 17. |
- Mukherjee, Oindrilla, et al.
(författare)
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A fusion protein derived from Moraxella catarrhalis and Neisseria meningitidis aimed for immune modulation of human B cells
- 2015
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Ingår i: Human Vaccines & Immunotherapeutics. - : Informa UK Limited. - 2164-5515 .- 2164-554X. ; 11:9, s. 2223-2227
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella IgD-binding protein (MID) is a well characterized trimeric autotransporter that specifically targets the IgD of B cells. We fused the membrane anchor of the meningococcal autotransporter NhhA with the IgD-binding region of MID (aa 962-1200) to create a chimeric protein designated as NID. The aim was to use this specific targeting to provide a better vaccine candidate against meningococci, in particular serogroup B by enhancing the immunogenicity of NhhA. NID was thereafter recombinantly expressed in E. coli. The NID-expressing E. coli bound to peripheral B lymphocytes that resulted in cellular activation. Furthermore, we also successfully expressed NID on outer membrane vesicles, nanoparticles that are commonly used in meningococcal vaccines. This study thus highlights the applicability of the menigococcal-Moraxella fusion protein NID to be used for specific targeting of vaccine components to the IgD B cell receptor.
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| 18. |
- Paulsson, Magnus, et al.
(författare)
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A novel vitronectin-binding protein of Pseudomonas aeruginosa for effective infection of the airways
- 2015
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Ingår i: ; , s. 0456-0456
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Konferensbidrag (refereegranskat)abstract
- Objectives Pseudomonas aeruginosa is a Gram-negative species that causes chronic and acute infections of the lung, skin, urinary tract and eyes. Most P. aeruginosa isolates are highly resistant to antibiotics and difficult to eradicate due to biofilm formation. The bacterium is known to utilize host proteins by diverse strategies in order to enhance its virulence. Vitronectin is a glycoprotein that is abundant in serum and the extracellular matrix, and is involved in cell adhesion, migration, tissue repair and regulation of the complement cascade. The concentration of vitronectin in the lung reflects the level of inflammation in patients with interstitial lung disease. Furthermore, the production is upregulated in patients with cystic fibrosis, which are often chronically colonised with P. aeruginosa. In this study, we analysed the vitronectin-binding capability of clinical strains and identified the P. aeruginosa surface proteins involved in vitronectin binding. Methods P. aeruginosa clinical isolates (n=64) from the airway (n=36), blood (n=15) and urine (n=13), in addition to the reference strain (PAO1) were analysed in a direct binding assay using [125I]-vitronectin. To identify the vitronectin-binding surface proteins of P. aeruginosa, the outer membrane proteins of PAO1 were separated by 2D-SDS-PAGE and western blotting. Vitronectin binding proteins of P. aeruginosa were recombinantly expressed in Escherichia coli and protein-protein interactions were evaluated by ELISA and flow cytometry. P. aeruginosa transposon mutants obtained from the “P. aeruginosa two-allele library” were analysed for vitronectin binding by [125I]-vitronectin or vitronectin coated to a glass surface. Results Our direct binding assay revealed that P. aeruginosa airway isolates bound significantly more vitronectin in comparison to blood (p=0.02) and urine isolates (p=0.04) (Fig. A). Using an approach consisting of 2D-SDS-PAGE and western blotting, we identified two outer membrane proteins that interacted with vitronectin (Fig. B). Expression of one of those (vitronectin binding protein 1; VnBp1) in an E. coli laboratory strain resulted in VnBp1 on the cell surface, and a vitronectin-binding phenotype. In addition, recombinantly expressed and purified VnBP1 showed a dose-dependent interaction with vitronectin in an ELISA (Fig. C). P. aeruginosa with a transposon insert in the vnBp1 gene bound significantly less vitronectin in comparison to the wild type (p=0.0009). Moreover, vnBp1 deficient mutants also showed significant reduced adherence to vitronectin coated glass slide (p≤0.001) in comparison to the wild type (Fig. D). Conclusions P. aeruginosa isolates cultured from the lung bind significantly more vitronectin in comparison to strains cultured from urine or blood. Vitronectin is recruited at the surface via VnBp1. This mechanism is likely to be of great importance for P. aeruginosa adhesion to the airway epithelial and basal lamina of disrupted airway epithelial cell layer and hence for the colonisation of the respiratory tract.
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| 19. |
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| 20. |
- Paulsson, Magnus, et al.
(författare)
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Peptidoglycan-Binding Anchor Is a Pseudomonas aeruginosa OmpA Family Lipoprotein With Importance for Outer Membrane Vesicles, Biofilms, and the Periplasmic Shape
- 2021
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The outer membrane protein A (OmpA) family contains an evolutionary conserved domain that links the outer membrane in Gram-negative bacteria to the semi-rigid peptidoglycan (PG) layer. The clinically significant pathogen Pseudomonas aeruginosa carries several OmpA family proteins (OprF, OprL, PA0833, and PA1048) that share the PG-binding domain. These proteins are important for cell morphology, membrane stability, and biofilm and outer membrane vesicle (OMV) formation. In addition to other OmpAs, in silico analysis revealed that the putative outer membrane protein (OMP) with gene locus PA1041 is a lipoprotein with an OmpA domain and, hence, is a potential virulence factor. This study aimed to evaluate PA1041 as a PG-binding protein and describe its effect on the phenotype. Clinical strains were confirmed to contain the lipoprotein resulting from PA1041 expression with Western blot, and PG binding was verified in enzyme-linked immunosorbent assay (ELISA). By using a Sepharose bead-based ELISA, we found that the lipoprotein binds to meso-diaminopimelic acid (mDAP), an amino acid in the pentapeptide portion of PGs. The reference strain PAO1 and the corresponding transposon mutant PW2884 devoid of the lipoprotein were examined for phenotypic changes. Transmission electron microscopy revealed enlarged periplasm spaces near the cellular poles in the mutant. In addition, we observed an increased release of OMV, which could be confirmed by nanoparticle tracking analysis. Importantly, mutants without the lipoprotein produced a thick, but loose and unorganized, biofilm in flow cells. In conclusion, the lipoprotein from gene locus PA1041 tethers the outer membrane to the PG layer, and mutants are viable, but display severe phenotypic changes including disordered biofilm formation. Based upon the phenotype of the P. aeruginosa PW2884 mutant and the function of the protein, we designate the lipoprotein with locus tag PA1041 as “peptidoglycan-binding anchor” (Pba).
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