Journal
EMBO JOURNAL
Volume 30, Issue 1, Pages 154-164Publisher
WILEY
DOI: 10.1038/emboj.2010.288
Keywords
bacterial cell division; chromosome segregation; FtsZ Z-ring formation; nucleoid occlusion; SImA
Categories
Funding
- MD Anderson Trust
- National Institutes of Health [GM068453, GM61074, T32 GM008280]
- MDA Institutional Core [CA16672]
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In Escherichia coli, cytokinesis is orchestrated by FtsZ, which forms a Z-ring to drive septation. Spatial and temporal control of Z-ring formation is achieved by the Min and nucleoid occlusion (NO) systems. Unlike the well-studied Min system, less is known about the anti-DNA guillotining NO process. Here, we describe studies addressing the molecular mechanism of SImA (synthetic lethal with a defective Min system)-mediated NO. SImA contains a TetR-like DNA-binding fold, and chromatin immunoprecipitation analyses show that SImA-binding sites are dispersed on the chromosome except the Ter region, which segregates immediately before septation. SImA binds DNA and FtsZ simultaneously, and the SImA-FtsZ structure reveals that two FtsZ molecules sandwich a SImA dimer. In this complex, FtsZ can still bind GTP and form protofilaments, but the separated protofilaments are forced into an anti-parallel arrangement. This suggests that SImA may alter FtsZ polymer assembly. Indeed, electron microscopy data, showing that SImA-DNA disrupts the formation of normal FtsZ polymers and induces distinct spiral structures, supports this. Thus, the combined data reveal how SImA derails Z-ring formation at the correct place and time to effect NO. The EMBO Journal (2011) 30, 154-164. doi:10.1038/emboj.2010.288; Published online 26 November 2010
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