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PLoS Biol. 2014 Oct 28;12(10):e1001977. doi: 10.1371/journal.pbio.1001977. eCollection 2014 Oct.

A DNA damage-induced, SOS-independent checkpoint regulates cell division in Caulobacter crescentus.

Author information

1
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
2
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.

Abstract

Cells must coordinate DNA replication with cell division, especially during episodes of DNA damage. The paradigm for cell division control following DNA damage in bacteria involves the SOS response where cleavage of the transcriptional repressor LexA induces a division inhibitor. However, in Caulobacter crescentus, cells lacking the primary SOS-regulated inhibitor, sidA, can often still delay division post-damage. Here we identify didA, a second cell division inhibitor that is induced by DNA damage, but in an SOS-independent manner. Together, DidA and SidA inhibit division, such that cells lacking both inhibitors divide prematurely following DNA damage, with lethal consequences. We show that DidA does not disrupt assembly of the division machinery and instead binds the essential division protein FtsN to block cytokinesis. Intriguingly, mutations in FtsW and FtsI, which drive the synthesis of septal cell wall material, can suppress the activity of both SidA and DidA, likely by causing the FtsW/I/N complex to hyperactively initiate cell division. Finally, we identify a transcription factor, DriD, that drives the SOS-independent transcription of didA following DNA damage.

PMID:
25350732
PMCID:
PMC4211646
DOI:
10.1371/journal.pbio.1001977
[Indexed for MEDLINE]
Free PMC Article

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