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A protein vital for correct chloroplast division in plants is able to take on a similar role in bacterial cells, according to research published today in the open access journal BMC Microbiology. The Arabidopsis thaliana Min protein (AtMinD) localizes in E. coli cells' polar regions keeping cell division at its correct central location, yet unlike its E. coli homologue, AtMinD does not oscillate.
Making certain that E. coli cells divide in the centre is down to Min proteins (MinC, D and E). MinE oscillates from the middle of the cell to one pole or another, driving the MinCD complex with it. The MinCD complex prevents FtsZ polymerization at the poles but not at the mid-line of the cell, where FtsZ ring formation leads to cell division.
A team of Beijing-based scientists expressed the Arabidopsis MinD gene (AtMinD), in E. coli cells that lacked the bacterial genes for both MinD and MinE. Surprisingly, the minicell phenotype of this E. coli HL1 mutant (MinDE) was rescued by the plant AtMinD gene, even though the dynamic MinE protein was absent. The Arabidopsis homologue AtMinD behaved differently from its E. coli counterpart in that it did not oscillate between poles, instead taking a stand at the pointed ends (puncta) of the poles of E. coli cells. The scientists went on to show that the rescue by plant AtMinD required E. coli MinC, and that AtMinD bound EcMinC in these puncta, This is another remarkable finding because while Arabidopsis (and other plants) encode plastid homologs of bacterial MinD and MinE, MinC is either absent or has diverged beyond recognition.
"The complementation of E. coli HL1 mutant (MinDE) by AtMinD and the requirement of EcMinC for this complementation suggest that the
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