title: Novel secretion apparatus maintains spore integrity and developmental gene expression in Bacillus subtilis.
abstract: Sporulation in Bacillus subtilis involves two cells that follow separate but coordinately regulated developmental programs. Late in sporulation, the developing spore (the forespore) resides within a mother cell. The regulation of the forespore transcription factor sigma(G) that acts at this stage has remained enigmatic. sigma(G) activity requires eight mother-cell proteins encoded in the spoIIIA operon and the forespore protein SpoIIQ. Several of the SpoIIIA proteins share similarity with components of specialized secretion systems. One of them resembles a secretion ATPase and we demonstrate that the ATPase motifs are required for sigma(G) activity. We further show that the SpoIIIA proteins and SpoIIQ reside in a multimeric complex that spans the two membranes surrounding the forespore. Finally, we have discovered that these proteins are all required to maintain forespore integrity. In their absence, the forespore develops large invaginations and collapses. Importantly, maintenance of forespore integrity does not require sigma(G). These results support a model in which the SpoIIIA-SpoIIQ proteins form a novel secretion apparatus that allows the mother cell to nurture the forespore, thereby maintaining forespore physiology and sigma(G) activity during spore maturation.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA, USA.
authors.forename: Thierry
authors.initials: T
authors.lastname: Doan
authors.forename: Cecile
authors.initials: C
authors.lastname: Morlot
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Meisner
authors.forename: Monica
authors.initials: M
authors.lastname: Serrano
authors.forename: Adriano O
authors.initials: AO
authors.lastname: Henriques
authors.forename: Charles P
authors.initials: CP
authors.lastname: Moran
authors.forename: David Z
authors.initials: DZ
authors.lastname: Rudner
mesh_terms: D001412:Bacillus subtilis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D055571:Secretory Pathway / Q000235:genetics / Q000502:physiology; D013171:Spores, Bacterial / Q000254:growth & development*; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors