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Filamentous Cells

YneA

SOS response is believe to be a universal bacteria phenomenon first studied in E.coli -LexA, recA

In Bacillus subtillis (gram positive) dinR protein is homologous to lexA (Repressor of din-damage inducible genes). din genes include uvrA, uvrB, dinB, dinC dinR and recA. DNA damage inhibits cell division.

Wild type Bacillus subtillis

dinR KO

dinR KO mutant over expressed the divergent (opposite direction) transcript for YneA, YneB and YnzC. These genes form the SOS regulon (recA independent SOS response)

YneA suppressed in wt without SOS induction

Expression of YneA from IPTG controlled promoter in wt leads to elongation.

Disruption of YneA in SOS response leads to reduced elongation. Altering YneB and YnzC expression does not affect cell morphology.

Double mutant (dinR YneA)

YneA protein required to suppress cell division. Not chromosome replication or segregation.

FtsZ is important for bacterial cell division forming a ring structure at the division site by polymerising assembling other proteins necessary for division at the site.

FtsZ localises to the cell division cycle unless dinR is disrupted or YneA is being induced.

YneA suppresses FtsZ ring formation- no proven direct interaction by two-hybrid.

Filamentous cells less colony formation.

YneA expression via the inactivation of dinR by Rec A is important.

Sequence of YneA: http://www.ncbi.nlm.nih.gov/nuccore/NC_000964.3?from=1918391&to=1918738&report=graph&content=5

Kawai, Y., Moriya, S., & Ogasawara, N. (2003). Identification of a protein, YneA, responsible for cell division suppression during the SOS response in Bacillus subtilis. Molecular microbiology, 47(4), 1113-22. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12581363.

MinCDJ

In B.subtilis cell division occurs precisely mid cell via the formation of the FtsZ ring (tubulin homologue), through Noc (Nucleoid occlusion: prevents division over nucleoids) and the min system (well described in E.coli), which prevents division taking place at the ends of the cell (poles).

Main function of Min system to prevent mini cell formation and ensuring only one cell division occurs per cell cycle.

Min’s role is not just in the inhibition of FtsZ. FtsZ recruits other components causing synthesis of the new wall and cell invagination.

Cell division is regulated spatially and temporally.

Min C inhibits FtsZ ring formation; Min C interacts with Min D via its C-terminal domain. Min C inhibits lateral interaction between the filaments.

Min D is a membrane associated ATPase. (Min E ensures high concentrations of MinCD at the poles in E.coli, no Min E homologue in B.subtilis! Instead DivIVA acts as a topological factor).

Min C in B.subtilis is responsible for localisation (shown using GFP) showed a primary site of localisation at the site of active division challenging the original model for the role of Min.

Min J was discovered linking Min D to DivIVA and therefore necessary for localisation.

Over expression of Min D in the absence of Min J causes lethal filamentation.

Min C sequence

http://www.ncbi.nlm.nih.gov/nuccore/NC_000964.3?from=2858550&to=2859298&strand=true&report=graph&content=5

http://www.ncbi.nlm.nih.gov/gene/937500

MinD sequence

http://www.ncbi.nlm.nih.gov/nuccore/NC_000964.3?from=2857736&to=2858622&strand=true&report=graph&content=5

http://www.ncbi.nlm.nih.gov/gene/937499

MinJ sequence

http://www.ncbi.nlm.nih.gov/nuccore/NC_000964.3?from=3620287&to=3621598&strand=true&report=graph&content=5

http://www.ncbi.nlm.nih.gov/gene/936668

van Baarle, S., & Bramkamp, M. (2010). The MinCDJ system in Bacillus subtilis prevents minicell formation by promoting divisome disassembly. PloS one, 5(3), e9850. doi: 10.1371/journal.pone.0009850.

Bramkamp, M. & van Baarle, S., 2009. Division site selection in rod-shaped bacteria. Current opinion in microbiology, 12(6), 683-8. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19884039.