title: The regulation of transcription of the gerA spore germination operon of Bacillus subtilis.
abstract: The gerA operon of Bacillus subtilis 168 comprises three genes concerned with the triggering of spore germination by L-alanine and its analogues. The expression of this operon has been characterized using chromosomal lacZ fusions to the gerA promoter. The gerA promoter is switched on 2.5-3 hours after the initiation of sporulation, in parallel with glucose dehydrogenase. A high proportion of the gerA-driven beta-galactosidase detected in sporulating cells is found in the mature spore; the gerA promoter is therefore active in the forespore compartment of the sporulating cell. The gerA promoter is not expressed in spoO, spoII or spoIIIA, B, E and G mutant backgrounds, but is expressed in spoIIIC and D and in spoIV and V mutants. The in vivo transcriptional startpoint of the operon has been mapped by primer extension experiments; sequences upstream from this startpoint show significant homology with recognition sequences for RNA polymerase containing sigma G (E sigma G). The gerA operon was transcribed in vitro by E sigma G with a startpoint identical to that used in vivo, and expression of the gerA operon was rapidly induced in vegetative cells by induction of sigma G synthesis. These data indicate that the gerA operon is an additional member of the sigma G regulon, which includes a number of genes expressed in parallel only in the forespore compartment of sporulating B. subtilis cells.
authors.affiliation: Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
authors.forename: I M
authors.initials: IM
authors.lastname: Feavers
authors.forename: J
authors.initials: J
authors.lastname: Foulkes
authors.forename: B
authors.initials: B
authors.lastname: Setlow
authors.forename: D
authors.initials: D
authors.lastname: Sun
authors.forename: W
authors.initials: W
authors.lastname: Nicholson
authors.forename: P
authors.initials: P
authors.lastname: Setlow
authors.forename: A
authors.initials: A
authors.lastname: Moir
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D002872:Chromosome Deletion; D005784:Gene Amplification; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D013171:Spores, Bacterial / Q000235:genetics; D014158:Transcription, Genetic