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Roles for both FtsA and the FtsBLQ subcomplex in FtsN ‐stimulated cell constriction in E scherichia coli
Author(s) -
Liu Bing,
Persons Logan,
Lee Lynda,
Boer Piet A. J.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12906
Subject(s) - periplasmic space , cytoplasm , microbiology and biotechnology , cell , cell division , biology , cell membrane , membrane protein , cell growth , chemistry , biochemistry , membrane , escherichia coli , gene
Summary E scherichia coli FtsN is a bitopic membrane protein that is essential for triggering active cell constriction. A small periplasmic subdomain ( E FtsN ) is required and sufficient for function, but its mechanism of action is unclear. We isolated extragenic E FtsN *‐suppressing mutations that restore division in cells producing otherwise non‐functional variants of FtsN . These mapped to the IC domain of FtsA in the cytoplasm and to small subdomains of the FtsB and FtsL proteins in the periplasm. All FtsB and FtsL variants allowed survival without E FtsN , but many then imposed a new requirement for interaction between the cytoplasmic domain of FtsN ( N FtsN ) and FtsA . Alternatively, variants of FtsA , FtsB or FtsL acted synergistically to allow cell division in the complete absence of FtsN . Strikingly, moreover, substitution of a single residue in FtsB ( E 56) proved sufficient to rescue Δ fts N cells as well. In FtsN + cells, E FtsN *‐suppressing mutations promoted cell fission at an abnormally small cell size, and caused cell shape and integrity defects under certain conditions. This and additional evidence support a model in which FtsN acts on either side of the membrane to induce a conformational switch in both FtsA and the FtsBLQ subcomplex to de‐repress septal peptidoglycan synthesis and membrane invagination.