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Team:Warsaw/Stage2/Background
From 2010.igem.org
MinC
MinC is the component of MinCDE system. Together with nucleoid occlusion it ensures that cell division will occur in the middle of a cell. Three proteins – MinC, MinD and MinE play different role[s] in preventing formation of division complex too close to cell poles [1]. MinC is directly responsible for stopping the early stage of division by inhibiting the polymerization of FtsZ protein monomers into a structure known as the Z-ring [8].
FtsZ is a tubuline homologue capable of creating chains, lariats and rings independently of other cellular factors [3]. The stability and decay of these structures is dependent on GTPase activity of FtsZ proteins [7]. At the beginning of cell division FtsZ monomers form the Z-ring to which other proteins responsible for the division are recruited. The presence of N-terminal domain of MinC prevents additional Z-rings from being established [9].
In bacterial cells MinC is recruited to membrane by the second protein of the system – MinD. This process involves C-terminal domain of MinC, which is also responsible for its oligomerisation. Recruitment to membrane is necessary for the inhibiting effect to occur at the physiological concentration of protein [4]. Finally the third protein - MinE - is responsible for keeping the MinCD complex from acting in the midcell region, thus enabling the formation of Z-ring in the proper location [5]. It was shown that mutants in either minC or minD divide at cell pole much more often than wild type, resulting in creation of nucleoid-free minicells. This mutations, however are not lethal because enough of the cells in population divide properly to sustain growth [6].
Although MinCDE is mostly analysed in E.coli, it’s elements were found in many different bacteria groups including Proteobacteria, Deinococcus-Thermus and Firmicutes phyla [1]. In B. subtilis the MinE protein is replaced by DivIVa which locates itself at the cell poles and with help of MinJ binds MinCD complex, decreasing it’s concentration at midcell [2].
When expressed at high level MinC is capable of preventing bacterial cell from dividing. As a result, of this the cell becomes filamentus. This effect requires only high level of MinC, not MinD. It has been proven that overexpression of C-terminal domain of MinC alone is sufficient to inhibit cell division [9].
1. “Themes and variations in prokaryotic cell division”, William Margolin, FEMS Microbiology Reviews 24 (2000) 531-548
2. “The MinCDJ System in Bacillus subtilis Prevents Minicell Formation by Promoting Divisome Disassembly”, Suey van Baarle and Marc Bramkami, PLoS One. 5 (2010)
3. “The bacterial cell division protein FtsZ assembles into cytoplasmic ring in fission yeast”, Ramanujam Srinivasan et al. Genes Dev. 22 (2008) 1741-1746
4. “The Switch I and II Regions of MinD Are Required for Binding and Activating MinC”, Huaijin Zhou and Joe Lutkenhaus, J Bacteriol. 186 (2004) 1546–1555.
5. “The MinE ring required for proper placement of the division site is a mobile structure that changes its cellular location during the Escherichia coli division cycle.”, Fu X et al. Proc. Natl. Acad. Sci. U S A 98. (2001)
6. “FtsZ ring cluster in min and partition mutants: Role of both the Min system and the nucleoid in regulation FtsZ ring location”, Yu et al. Mol. Microbiol. 32 (1999) 315-326
7. “FtsZ from Divergent Foreign Bacteria Can Function for Cell Division in Escherichia coli”, Masaki Osawa and Harold P. Erickson, J. Bacteriol. 188 (2006) 7132-7140
8. “FtsZ, a tubulin homologue in prokaryote division”, Harold P. Erickson.Trends. Cell Biol. 7 (1997) 362-367
9. “Analysis of MinC Reveals Two Independent Domains Involved in Interaction with MinD and FtsZ”, Zonglin Hu and Joe Lutkenhaus, J. Bacteriol. 182 (2000) 3965-3971
