| 1. |
- Matarredona, Laura, et al.
(author)
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Global Lrp regulator protein from Haloferax mediterranei: Transcriptional analysis and structural characterization
- 2024
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In: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 260
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Journal article (peer-reviewed)abstract
- Haloferax mediterranei, an extreme halophilic archaeon thriving in hypersaline environments, has acquired significant attention in biotechnological and biochemical research due to its remarkable ability to flourish in extreme salinity conditions. Transcription factors, essential in regulating diverse cellular processes, have become focal points in understanding its adaptability. This study delves into the role of the Lrp transcription factor, exploring its modulation of glnA, nasABC, and lrp gene promoters in vivo through β-galactosidase assays. Remarkably, our findings propose Lrp as the pioneering transcriptional regulator of nitrogen metabolism identified in a haloarchaeon. This study suggests its potential role in activating or repressing assimilatory pathway enzymes (GlnA and NasA). The interaction between Lrp and these promoters is analyzed using Electrophoretic Mobility Shift Assay and Differential Scanning Fluorimetry, highlighting L-glutamine's indispensable role in stabilizing the Lrp-DNA complex. Our research uncovers that halophilic Lrp forms octameric structures in the presence of L-glutamine. The study reveals the three-dimensional structure of the Lrp as a homodimer using X-ray crystallography, confirming this state in solution by Small-Angle X-ray Scattering. These findings illuminate the complex molecular mechanisms driving Hfx. mediterranei's nitrogen metabolism, offering valuable insights about its gene expression regulation and enriching our comprehension of extremophile biology.
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| 2. |
- Båth, Petra, 1988, et al.
(author)
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Lipidic cubic phase serial femtosecond crystallography structure of a photosynthetic reaction centre
- 2022
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In: Acta Crystallographica Section D-Structural Biology. - : International Union of Crystallography (IUCr). - 2059-7983. ; 78, s. 698-708
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Journal article (peer-reviewed)abstract
- Serial crystallography is a rapidly growing method that can yield structural insights from microcrystals that were previously considered to be too small to be useful in conventional X-ray crystallography. Here, conditions for growing microcrystals of the photosynthetic reaction centre of Blastochloris viridis within a lipidic cubic phase (LCP) crystallization matrix that employ a seeding protocol utilizing detergent-grown crystals with a different crystal packing are described. LCP microcrystals diffracted to 2.25 angstrom resolution when exposed to XFEL radiation, which is an improvement of 0.15 angstrom over previous microcrystal forms. Ubiquinone was incorporated into the LCP crystallization media and the resulting electron density within the mobile Q(B) pocket is comparable to that of other cofactors within the structure. As such, LCP microcrystallization conditions will facilitate time-resolved diffraction studies of electron-transfer reactions to the mobile quinone, potentially allowing the observation of structural changes associated with the two electron-transfer reactions leading to complete reduction of the ubiquinone ligand.
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| 3. |
- Ahlberg Gagnér, Viktor, 1989, et al.
(author)
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Clustering of atomic displacement parameters in bovine trypsin reveals a distributed lattice of atoms with shared chemical properties
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- Low-frequency vibrations are crucial for protein structure and function, but only a few experimental techniques can shine light on them. The main challenge when addressing protein dynamics in the terahertz domain is the ubiquitous water that exhibit strong absorption. In this paper, we observe the protein atoms directly using X-ray crystallography in bovine trypsin at 100 K while irradiating the crystals with 0.5 THz radiation alternating on and off states. We observed that the anisotropy of atomic displacements increased upon terahertz irradiation. Atomic displacement similarities developed between chemically related atoms and between atoms of the catalytic machinery. This pattern likely arises from delocalized polar vibrational modes rather than delocalized elastic deformations or rigid-body displacements. The displacement correlation between these atoms were detected by a hierarchical clustering method, which can assist the analysis of other ultra-high resolution crystal structures. These experimental and analytical tools provide a detailed description of protein dynamics to complement the structural information from static diffraction experiments. © 2019, The Author(s).
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| 4. |
- Chandrasekaran, Venkatagaran, et al.
(author)
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Cohesin-Mediated Chromatin Interactions and Autoimmunity
- 2022
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In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
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Journal article (peer-reviewed)abstract
- Proper physiological functioning of any cell type requires ordered chromatin organization. In this context, cohesin complex performs important functions preventing premature separation of sister chromatids after DNA replication. In partnership with CCCTC-binding factor, it ensures insulator activity to organize enhancers and promoters within regulatory chromatin. Homozygous mutations and dysfunction of individual cohesin proteins are embryonically lethal in humans and mice, which limits in vivo research work to embryonic stem cells and progenitors. Conditional alleles of cohesin complex proteins have been generated to investigate their functional roles in greater detail at later developmental stages. Thus, genome regulation enabled by action of cohesin proteins is potentially crucial in lineage cell development, including immune homeostasis. In this review, we provide current knowledge on the role of cohesin complex in leukocyte maturation and adaptive immunity. Conditional knockout and shRNA-mediated inhibition of individual cohesin proteins in mice demonstrated their importance in haematopoiesis, adipogenesis and inflammation. Notably, these effects occur rather through changes in transcriptional gene regulation than through expected cell cycle defects. This positions cohesin at the crossroad of immune pathways including NF-kB, IL-6, and IFN gamma signaling. Cohesin proteins emerged as vital regulators at early developmental stages of thymocytes and B cells and after antigen challenge. Human genome-wide association studies are remarkably concordant with these findings and present associations between cohesin and rheumatoid arthritis, multiple sclerosis and HLA-B27 related chronic inflammatory conditions. Furthermore, bioinformatic prediction based on protein-protein interactions reveal a tight connection between the cohesin complex and immune relevant processes supporting the notion that cohesin will unearth new clues in regulation of autoimmunity.
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| 5. |
- Erlandsson, Malin, 1972, et al.
(author)
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Survivin promotes a glycolytic switch in CD4+ T cells by suppressing the transcription of PFKFB3 in rheumatoid arthritis.
- 2022
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In: iScience. - : Elsevier BV. - 2589-0042. ; 25:12
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Journal article (peer-reviewed)abstract
- In this study, we explore the role of nuclear survivin in maintaining the effector phenotype of IFNγ-producing Tcells acting through the transcriptional control of glucose utilization. High expression of survivin in CD4+T cells was associated with IFNγ-dependent phenotype and anaerobic glycolysis. Transcriptome of CD4+ cells and sequencing of survivin-bound chromatin showed that nuclear survivin had a genome-wide and motif-specific binding to regulatory regions of the genes controlling cell metabolism. Survivin coprecipitates with transcription factors IRF1 and SMAD3, which repressed the transcription of the metabolic check-point enzyme phosphofructokinase 2 gene PFKFB3 and promoted anaerobic glycolysis. Combining transcriptome analyses of CD4+ cells and functional studies in glucose metabolism, we demonstrated that the inhibition of survivin reverted PFKFB3 production, inhibited glucose uptake, and reduces interferon effects in CD4+ cells. These results present a survivin-dependent mechanism in coordinating the metabolic adaptation of CD4+T cells and propose an attractive strategy to counteract IFNγ-dependent inflammation in autoimmunity.
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| 6. |
- Garcia-Bonete, Maria-Jose, 1989, et al.
(author)
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Bayesian Analysis of MicroScale Thermophoresis Data to Quantify Affinity of Protein: Protein Interactions with Human Survivin
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7:1, s. Art. no. 16816-
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Journal article (peer-reviewed)abstract
- A biomolecular ensemble exhibits different responses to a temperature gradient depending on its diffusion properties. MicroScale Thermophoresis technique exploits this effect and is becoming a popular technique for analyzing interactions of biomolecules in solution. When comparing affinities of related compounds, the reliability of the determined thermodynamic parameters often comes into question. The thermophoresis binding curves can be assessed by Bayesian inference, which provides a probability distribution for the dissociation constant of the interacting partners. By applying Bayesian machine learning principles, binding curves can be autonomously analyzed without manual intervention and without introducing subjective bias by outlier rejection. We demonstrate the Bayesian inference protocol on the known survivin: borealin interaction and on the putative protein-protein interactions between human survivin and two members of the human Shugoshin-like family (hSgol1 and hSgol2). These interactions were identified in a protein microarray binding assay against survivin and confirmed by MicroScale Thermophoresis.
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| 7. |
- Gravina, Giacomo, et al.
(author)
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Survivin in autoimmune diseases.
- 2017
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In: Autoimmunity reviews. - : Elsevier BV. - 1873-0183 .- 1568-9972. ; 16:8, s. 845-855
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Research review (peer-reviewed)abstract
- Survivin is a protein functionally important for cell division, apoptosis, and possibly, for micro-RNA biogenesis. It is an established marker of malignant cell transformation. In non-malignant conditions, the unique properties of survivin make it indispensable for homeostasis of the immune system. Indeed, it is required for the innate and adaptive immune responses, controlling differentiation and maintenance of CD4(+) and CD8(+) memory T-cells, and in B cell maturation. Recently, survivin has emerged as an important player in the pathogenesis of autoimmune diseases. Under the conditions of unreserved inflammation, survivin enhances antigen presentation, maintains persistence of autoreactive cells, and supports production of autoantibodies. In this context, survivin takes its place as a diagnostic and prognostic marker in rheumatoid arthritis, psoriasis, systemic sclerosis and pulmonary arterial hypertension, neuropathology and multiple sclerosis, inflammatory bowel diseases and oral lichen planus. In this review, we summarise the knowledge about non-malignant properties of survivin and focus on its engagement in cellular and molecular pathology of autoimmune diseases. The review highlights utility of survivin measures for clinical applications. It provides rational for the survivin inhibiting strategies and presents results of recent reports on survivin inhibition in modern therapies of cancers and autoimmune diseases.
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| 8. |
- Jensen, Maja, 1978, et al.
(author)
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High-resolution macromolecular crystallography at the FemtoMAX beamline with time-over-threshold photon detection
- 2021
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In: Journal of Synchrotron Radiation. - 1600-5775 .- 0909-0495. ; 28, s. 64-70
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Journal article (peer-reviewed)abstract
- Protein dynamics contribute to protein function on different time scales. Ultrafast X-ray diffraction snapshots can visualize the location and amplitude of atom displacements after perturbation. Since amplitudes of ultrafast motions are small, high-quality X-ray diffraction data is necessary for detection. Diffraction from bovine trypsin crystals using single femtosecond X-ray pulses was recorded at FemtoMAX, which is a versatile beamline of the MAX IV synchrotron. The time-over-threshold detection made it possible that single photons are distinguishable even under short-pulse low-repetition-rate conditions. The diffraction data quality from FemtoMAX beamline enables atomic resolution investigation of protein structures. This evaluation is based on the shape of the Wilson plot, cumulative intensity distribution compared with theoretical distribution, I/σ, Rmerge /Rmeas and CC1/2 statistics versus resolution. The FemtoMAX beamline provides an interesting alternative to X-ray free-electron lasers when studying reversible processes in protein crystals.
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| 9. |
- Jensen, Maja, 1978, et al.
(author)
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Survivin prevents the polycomb repressor complex 2 from methylating histone 3 lysine 27
- 2023
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In: Iscience. ; 26:7
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Journal article (peer-reviewed)abstract
- This study investigates the role of survivin in epigenetic control of gene transcription through interaction with the polycomb repressive complex 2 (PRC2). PRC2 is responsible for silencing gene expression by trimethylating lysine 27 on histone 3. We observed differential expression of PRC2 subunits in CD4(+) T cells with varying levels of survivin expression, and ChIP-seq results indicated that survivin colocalizes with PRC2 along DNA. Inhibition of survivin resulted in a significant increase in H3K27 trimethylation, implying that survivin prevents PRC2 from functioning. Peptide microarray showed that survivin interacts with peptides from PRC2 subunits, and machine learning revealed that amino acid composition contains relevant information for predicting survivin interaction. NMR and BLI experiments supported the interaction of survivin with PRC2 subunit EZH2. Finally, protein-protein docking revealed that the survivin-EZH2 interaction interface overlaps with catalytic residues of EZH2, potentially inhibiting its H3K27 methylation activity. These findings suggest that survivin inhibits PRC2 function.
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| 10. |
- Larasati Anindya, Atsarina, et al.
(author)
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Bayesian progress curve analysis of MicroScale thermophoresis data
- 2022
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In: Digital Discovery. - : Royal Society of Chemistry (RSC). - 2635-098X. ; 1:3, s. 325-332
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Journal article (peer-reviewed)abstract
- MicroScale Thermophoresis (MST) follows the movement of fluorescent-labelled biomolecules with different sizes along a temperature gradient. The presence of a “contrary trend” pattern, that is, the trend of fluorescence change reversing at higher titrant concentrations, is a well-known problem with uncertain cause. Conventionally, binding curves and kinetic parameters are derived from MST datasets using regression analysis on isolated time windows, while the rest of the data are ignored, and the “contrary trend” fluorescent levels are also usually removed as outliers. This biased approach can be avoided with a more continuous analysis of the entire kinetic process. The Bayesian model of MST progress curves allows the inference of parameters and modelling of the whole experiment. The removal of unusual data points is unnecessary once the anomalous kinetic process is identified. This alternative data analysis approach was applied to our MST datasets from survivin–hSgol2 interactions, and the results show that the binding curves remained sigmoid when all data were included. We were also able to infer the value and uncertainty of the dissociation constant (KD) by ascribing the anomalous data points to a new, linear kinetic component. This approach demonstrates good posterior predictions from the MST process in both short and longer experiments as well as the feasibility of KD inference from short experiments.
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