title: How the early sporulation sigma factor sigmaF delays the switch to late development in Bacillus subtilis.
abstract: Sporulation in Bacillus subtilis is a primitive differentiation process involving two cell types, the forespore and the mother cell. Each cell implements two successive transcription programmes controlled by specific sigma factors. We report that activity of sigma(G), the late forespore sigma factor, is kept in check by Gin, the product of csfB, a gene controlled by sigma(F), the early forespore sigma factor. Gin abolishes sigma(G) transcriptional activity when sigma(G) is artificially synthesized during growth, but has no effect on sigma(F). Gin interacts strongly with sigma(G) but not with sigma(F) in a yeast two-hybrid experiment. The absence of Gin allows sigma(G) to be active during sporulation independently of the mother-cell development to which it is normally coupled. Premature sigma(G) activity leads to the formation of slow-germinating spores, and complete deregulation of sigma(G) synthesis is lethal when combined with gin inactivation. Gin allows sigma(F) to delay the switch to the late forespore transcription programme by preventing sigma(G) to take over before the cell has reached a critical stage of development. A similar strategy, following a completely unrelated route, is used by the mother cell.
authors.affiliation: Université Paris-Diderot, CNRS-UPR9073, Institut de Biologie Physico-Chimique, 75005 Paris, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Karmazyn-Campelli
authors.forename: Lamya
authors.initials: L
authors.lastname: Rhayat
authors.forename: Rut
authors.initials: R
authors.lastname: Carballido-López
authors.forename: Sandra
authors.initials: S
authors.lastname: Duperrier
authors.forename: Niels
authors.initials: N
authors.lastname: Frandsen
authors.forename: Patrick
authors.initials: P
authors.lastname: Stragier
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D005696:Galactosidases / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D012808:Sigma Factor / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C030069:spore-specific proteins, Bacillus; C063202:sporulation-specific sigma factors; D005696:Galactosidases