title: A novel factor controlling bistability in Bacillus subtilis: the YmdB protein affects flagellin expression and biofilm formation.
abstract: Cells of Bacillus subtilis can either be motile or sessile, depending on the expression of mutually exclusive sets of genes that are required for flagellum or biofilm formation, respectively. Both activities are coordinated by the master regulator SinR. We have analyzed the role of the previously uncharacterized ymdB gene for bistable gene expression in B. subtilis. We observed a strong overexpression of the hag gene encoding flagellin and of other genes of the σ(D)-dependent motility regulon in the ymdB mutant, whereas the two major operons for biofilm formation, tapA-sipW-tasA and epsA-O, were not expressed. As a result, the ymdB mutant is unable to form biofilms. An analysis of the individual cells of a population revealed that the ymdB mutant no longer exhibited bistable behavior; instead, all cells are short and motile. The inability of the ymdB mutant to form biofilms is suppressed by the deletion of the sinR gene encoding the master regulator of biofilm formation, indicating that SinR-dependent repression of biofilm genes cannot be relieved in a ymdB mutant. Our studies demonstrate that lack of expression of SlrR, an antagonist of SinR, is responsible for the observed phenotypes. Overexpression of SlrR suppresses the effects of a ymdB mutation.
authors.affiliation: Department of General Microbiology, Georg August University Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Diethmaier
authors.forename: Nico
authors.initials: N
authors.lastname: Pietack
authors.forename: Katrin
authors.initials: K
authors.lastname: Gunka
authors.forename: Christoph
authors.initials: C
authors.lastname: Wrede
authors.forename: Martin
authors.initials: M
authors.lastname: Lehnik-Habrink
authors.forename: Christina
authors.initials: C
authors.lastname: Herzberg
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hübner
authors.forename: Jörg
authors.initials: J
authors.lastname: Stülke
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D005408:Flagellin / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D018085:Regulon
chemical_list: D001426:Bacterial Proteins; D005408:Flagellin; C076733:FlaD protein, Bacteria