Publications by authors named "Imrich Barak"
During sporulation, Bacillus subtilis forms an asymmetric septum, dividing the cell into two compartments, a mother cell and a forespore. The site of asymmetric septation is linked to the membrane where FtsZ and SpoIIE initiate the formation of the Z-ring and the E-ring, respectively. These rings then serve as a scaffold for the other cell division and peptidoglycan synthesizing proteins needed to build the septum.
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- Streptococcus agalactiae (GBS) is a significant cause of infections in newborns and can also colonize adults in the gastrointestinal and urogenital tracts, leading to complicated antibiotic treatments due to resistant strains.
- Researchers isolated a unique endolysin called EN534 from a human strain of GBS, which has a structure designed for breaking down bacterial cell walls.
- The EN534 endolysin showed effectiveness in lysing GBS and other bacteria without harming beneficial vaginal bacteria, suggesting its potential as a new treatment option for GBS infections.
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- The European XFEL and LCLS II are powerful X-ray sources that can collect detailed data from crystals at rapid megahertz rates.
- Researchers used these X-ray pulses to gather two complete datasets from a single lysozyme crystal in less than 1 microsecond, achieving high-resolution structures.
- The comparison of these structures showed no radiation damage or significant changes, indicating that this multi-hit SFX technique can effectively capture fast structural changes in crystals.
Chromium of anthropogenic origin contaminates the environment worldwide. The toxicity of chromium, a group I human carcinogen, is greatest when it is in a hexavalent oxidation state, Cr(VI). Cr(VI) is actively transported into the cell, triggering oxidative damage intracellularly.
View Article and Find Full Text PDFhas served as a model microorganism for many decades [...
View Article and Find Full Text PDFDivIVA is a protein initially identified as a spatial regulator of cell division in the model organism , but its homologues are present in many other Gram-positive bacteria, including species. Besides its role as topological regulator of the Min system during bacterial cell division, DivIVA is involved in chromosome segregation during sporulation, genetic competence, and cell wall synthesis. DivIVA localizes to regions of high membrane curvature, such as the cell poles and cell division site, where it recruits distinct binding partners.
View Article and Find Full Text PDFThe science of X-ray free-electron lasers (XFELs) critically depends on the performance of the X-ray laser and on the quality of the samples placed into the X-ray beam. The stability of biological samples is limited and key biomolecular transformations occur on short timescales. Experiments in biology require a support laboratory in the immediate vicinity of the beamlines.
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- - Endospores, highly resistant cells, have two protective layers: a peptidoglycan cortex and a protein-rich spore coat, which are formed through a process dependent on proteins SpoIVA and SpoVM.
- - The research found that mutant spores lacking the alanine racemase gene YncD had decreased resistance to heat and exhibited altered germination in the presence of l-alanine compared to wild-type spores.
- - Additionally, the study revealed that SpoVM interacts with SpoIVA and a penicillin-binding protein, SpoVD, suggesting a link between the formation of the coat and cortex in bacteria.
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDFDiffraction pattern of Bacillus subtilis CotY spore coat protein 2D crystals.
Colloids Surf B Biointerfaces
January 2021
Bacillus subtilis spore coat is a bacterial proteinaceous structure with amazing characteristics of self-organization, unique resiliency, toughness and flexibility in the same time. The spore coat represents a complex multilayered protein structure which is composed of over 80 coat proteins. Some of these proteins form two dimensional crystal structures who's low resolution ternary structure as was determined by electron microscopy.
View Article and Find Full Text PDFBacterial nanotubes are membranous structures that have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here, we investigate the morphology and formation of bacterial nanotubes using Bacillus subtilis. We show that nanotube formation is associated with stress conditions, and is highly sensitive to the cells' genetic background, growth phase, and sample preparation methods.
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- This study employs advanced imaging techniques to investigate the role of the SpoIIE protein in the development of bacteria during asymmetric cell division and sporulation.
- Using single-molecule optical proteomics, researchers discovered that SpoIIE forms tetramers and clusters, with its quantity increasing as the bacteria progress in sporulation, impacting gene expression and protein activity.
- The findings highlight the complexity of SpoIIE's functions and suggest that its organization allows for versatile roles in cellular processes, illustrating the benefits of live cell tracking for understanding biological mechanisms.
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- Peptidoglycan is essential for determining bacterial cell shape and is crucial for cell elongation and division, particularly in rod-shaped bacteria.
- During sporulation, an asymmetric cell division occurs, involving a unique septum that differs from the vegetative septum both in structure and protein composition.
- The study highlights a direct relationship between the sporulation protein SpoIIE and GpsB, suggesting they form a multi-protein complex that connects peptidoglycan synthesis to the morphogenetic changes needed for forespore formation.
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- * Most strains belonged to 12 different species and 8 genera, primarily identified as part of the Bacillus cereus group, suggesting a general high chromate tolerance among these bacteria.
- * Two specific strains, NCr1a and PCr12, not only grew well in Cr(VI) media but also showed high capacities for chromium removal, making them valuable for further research on chromate tolerance and potential bioremediation strategies.
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- - Bacillus subtilis is a rod-shaped bacterium that divides symmetrically at mid-cell during vegetative growth and can also divide asymmetrically during sporulation.
- - The asymmetric division during sporulation creates a smaller forespore and a larger mother cell, which is essential for different gene expression.
- - While we have a good understanding of the cell division process during vegetative growth, knowledge about how the site of asymmetric division is determined during sporulation is still limited.
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- The European X-ray Free-Electron Laser (XFEL) is the first of its kind to deliver X-ray pulses at megahertz pulse rates, vastly improving on previous technologies.
- Researchers have successfully measured high-quality diffraction data at these new pulse rates, validating the laser's capabilities.
- Two complete datasets were collected: one from lysozyme and another from a β-lactamase complex, demonstrating the potential for advanced structural analysis and dynamic measurements in molecular science.
Probably one of the most controversial questions about the cell division of Bacillus subtilis, a rod-shaped bacterium, concerns the mechanism that ensures correct division septum placement-at mid-cell during vegetative growth but closer to one end during sporulation. In general, bacteria multiply by binary fission, in which the division septum forms almost exactly at the cell centre. How the division machinery achieves such accuracy is a question of continuing interest.
View Article and Find Full Text PDFOne of the key regulators ensuring proper Z-ring placement in rod-shaped bacteria is the Min system. It does so by creating a concentration gradient of the MinC septation inhibitor along the cell axis. In Escherichia coli, this gradient is established by a MinE-mediated pole-to-pole oscillation of the MinCDE complex.
View Article and Find Full Text PDFVegetative cell division in takes place precisely at the middle of the cell to ensure that two viable daughter cells are formed. The first event in cell division is the positioning of the FtsZ Z-ring at the correct site. This is controlled by the coordinated action of both negative and positive regulators.
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- - Bacillus subtilis spores have a robust structure with a thick protein layer called the spore coat, made up of over 80 proteins organized into four layers: basement, inner coat, outer coat, and crust.
- - During spore development, proteins from the cytoplasm are deposited onto the prespore surface, with certain morphogenetic proteins forming a scaffold for the other proteins.
- - This study used a bacterial two-hybrid system to explore interactions among proteins in the outer coat and crust, revealing self-interactions and novel contacts that could help clarify the roles of proteins like CotE, CotY, and CotZ in spore coat development.
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- Spores of certain clostridial species pose a significant risk in the food industry due to their ability to withstand heat treatment, which is tied to their hydration levels and the presence of calcium and dipicolinic acid (DPA).
- Research shows variations in heat resistance and DPA/calcium content among different clostridial strains, with some strains having low levels of these components and consequently low heat resistance.
- Furthermore, the study reveals that these calcium and DPA levels can vary not only between different strains but also among individual spores within the same population, suggesting a complex relationship between spore resistance and their biochemical composition.
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- The process of sporulation in Bacillus subtilis begins with the formation of an asymmetric septum, which is crucial for activating the transcription factor σF in one of the daughter cells.
- The protein SpoIIE is essential for this activation, but the study highlights the additional role of the morphogenic protein RodZ in both the asymmetric septum formation and σF activation.
- RodZ interacts directly with SpoIIE, suggesting that they may form a complex that coordinates the changes in cell shape and triggers the necessary developmental steps for spore formation.
The spore of Bacillus subtilis, a dormant type of cell, is surrounded by a complex multilayered protein structure known as the coat. It is composed of over 70 proteins and essential for the spore to withstand extreme environmental conditions and allow germination under favorable conditions. However, understanding how the properties of the coat arise from the interactions among all these proteins is an important challenge.
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- The SpoIISABC system in bacteria, first found in Bacillus subtilis, includes a toxic protein (SpoIISA) and two neutralizing antitoxins (SpoIISB and SpoIISC).
- A bioinformatics analysis explores how these genes are distributed across different species, identifying conserved regions and relationships between them.
- This system is core to the Bacillus genus but can also be found in non-Bacillus species due to horizontal gene transfer, with SpoIISB and SpoIISC evolving from gene duplications in separate lineages.