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. However, despite decades of research, not enough is known about how the asymmetric septation site is determined. Here, we identified and characterized the interaction between SpoIIE and RefZ. We show that these two proteins transiently colocalize during the early stages of asymmetric septum formation when RefZ localizes primarily from the mother cell side of the septum. We propose that these proteins and their interplay with the spatial organization of the chromosome play a role in controlling asymmetric septum positioning.
DivIVA is a protein initially identified as a spatial regulator of cell division in the model organism Bacillus subtilis, but its homologues are present in many other Gram-positive bacteria, including Clostridia 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. Previously, it was suggested that negative curvature sensing is the main mechanism by which DivIVA binds to these specific regions. Here, we show that Clostridioides difficile DivIVA binds preferably to membranes containing negatively charged phospholipids, especially cardiolipin. Strikingly, we observed that upon binding, DivIVA modifies the lipid distribution and induces changes to lipid bilayers containing cardiolipin. Our observations indicate that DivIVA might play a more complex and so far unknown active role during the formation of the cell division septal membrane.
- MeSH
- bakteriální proteiny metabolismus MeSH
- buněčná membrána metabolismus MeSH
- Clostridioides difficile růst a vývoj metabolismus MeSH
- kardiolipiny metabolismus MeSH
- membránové lipidy metabolismus MeSH
- proteiny buněčného cyklu metabolismus MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
- Publikační typ
- tisková chyba MeSH
Bacterial 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. Remarkably, nanotubes appear to be extruded exclusively from dying cells, likely as a result of biophysical forces. Their emergence is extremely fast, occurring within seconds by cannibalizing the cell membrane. Subsequent experiments reveal that cell-to-cell transfer of non-conjugative plasmids depends strictly on the competence system of the cell, and not on nanotube formation. Our study thus supports the notion that bacterial nanotubes are a post mortem phenomenon involved in cell disintegration, and are unlikely to be involved in cytoplasmic content exchange between live cells.
The thioredoxin system is a significant redox regulator in all organisms. Thioredoxins in bacteria are the major dithiol reductants in the cytosol (or an advanced equivalent to dithiotreitol of cells) thanks to the low redox potentials (Holmgren, 1985). In the genome of the studied model Streptomyces coelicolor A3(2) several genes were revealed which code proteins forming the thioredoxin system. It seems that this gram-positive soil bacteria have a very complex redox system, with a variety of reducing possibilities. In this work cloning, purification and characterization of further thioredoxins (TrxA2 and TrxA3) are described. Both proteins were overexpressed in E. coli cytoplasma as soluble active hexahistidine fusion proteins and isolated as homogenous substances.
Bacillus subtilis, a Gram-positive bacterium commonly found in soil, is an excellent model organism for the study of basic cell processes, such as cell division and cell differentiation, called sporulation. In B. subtilis the essential genetic information is carried on a single circular chromosome, the correct segregation of which is crucial for both vegetative growth and sporulation. The proper completion of life cycle requires each daughter cell to obtain identical genetic information. The consequences of inaccurate chromosome segregation can lead to formation of anucleate cells, cells with two chromosomes, or cells with incomplete chromosomes. Although bacteria miss the classical eukaryotic mitotic apparatus, the chromosome segregation is undeniably an active process tightly connected to other cell processes as DNA replication and compaction. To fully understand the chromosome segregation, it is necessary to study this process in a wider context and to examine the role of different proteins at various cell life cycle stages. The life cycle of B. subtilis is characteristic by its specific cell differentiation process where, two slightly different segregation mechanisms exist, specialized in vegetative growth and in sporulation.
- MeSH
- Bacillus subtilis genetika izolace a purifikace MeSH
- chromozomální proteiny, nehistonové genetika izolace a purifikace MeSH
- financování organizované využití MeSH
- grampozitivní sporulující bakterie genetika izolace a purifikace růst a vývoj MeSH
- histony genetika izolace a purifikace MeSH
- rac proteiny vázající GTP genetika izolace a purifikace MeSH
- segregace chromozomů genetika MeSH
- translokace genetická genetika MeSH
