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Nucleoid occlusion prevents cell division during replication fork arrest in Bacillus subtilis
Author(s) -
Bernard Remi,
Marquis Kathleen A.,
Rudner David Z.
Publication year - 2010
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/j.1365-2958.2010.07369.x
Subject(s) - biology , ftsz , nucleoid , cell division , microbiology and biotechnology , dna replication , bacillus subtilis , replisome , pre replication complex , genetics , control of chromosome duplication , cell , dna , gene , eukaryotic dna replication , bacteria , escherichia coli
Summary How bacteria respond to chromosome replication stress has been traditionally studied using temperature‐sensitive mutants and chemical inhibitors. These methods inevitably arrest all replication and lead to induction of transcriptional responses and inhibition of cell division. Here, we used repressor proteins bound to operator arrays to generate a single stalled replication fork. These replication roadblocks impeded replisome progression on one arm, leaving replication of the other arm and re‐initiation unaffected. Remarkably, despite robust generation of RecA–GFP filaments and a strong block to cell division during the roadblock, patterns of gene expression were not significantly altered. Consistent with these findings, division inhibition was not mediated by the SOS‐induced regulator YneA nor by RecA‐independent repression of ftsL . In support of the idea that nucleoid occlusion prevents inappropriate cell division during fork arrest, immature FtsZ‐rings formed adjacent to the DNA mass but rarely on top of it. Furthermore, mild alterations in chromosome compaction resulted in cell division that guillotined the DNA. Strikingly, the nucleoid occlusion protein Noc had no discernable role in division inhibition. Our data indicate that Noc‐independent nucleoid occlusion prevents inappropriate cell division during replication fork arrest. They further suggest that Bacillus subtilis normally manages replication stress rather than inducing a stress response.