title: Sporulation during growth in a gut isolate of Bacillus subtilis.
abstract: Sporulation by Bacillus subtilis is a cell density-dependent response to nutrient deprivation. Central to the decision of entering sporulation is a phosphorelay, through which sensor kinases promote phosphorylation of Spo0A. The phosphorelay integrates both positive and negative signals, ensuring that sporulation, a time- and energy-consuming process that may bring an ecological cost, is only triggered should other adaptations fail. Here we report that a gastrointestinal isolate of B. subtilis sporulates with high efficiency during growth, bypassing the cell density, nutritional, and other signals that normally make sporulation a post-exponential-phase response. Sporulation during growth occurs because Spo0A is more active per cell and in a higher fraction of the population than in a laboratory strain. This in turn, is primarily caused by the absence from the gut strain of the genes rapE and rapK, coding for two aspartyl phosphatases that negatively modulate the flow of phosphoryl groups to Spo0A. We show, in line with recent results, that activation of Spo0A through the phosphorelay is the limiting step for sporulation initiation in the gut strain. Our results further suggest that the phosphorelay is tuned to favor sporulation during growth in gastrointestinal B. subtilis isolates, presumably as a form of survival and/or propagation in the gut environment.
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Estação Agronómica Nacional, Oeiras, Portugal.
authors.forename: Cláudia R
authors.initials: CR
authors.lastname: Serra
authors.affiliation: Genome Sequencing and Analysis Program, The Broad Institute, Cambridge, Massachusetts, USA.
authors.forename: Ashlee M
authors.initials: AM
authors.lastname: Earl
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Estação Agronómica Nacional, Oeiras, Portugal.
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Barbosa
authors.affiliation: Department of Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Kolter
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Estação Agronómica Nacional, Oeiras, Portugal aoh@itqb.unl.pt.
authors.forename: Adriano O
authors.initials: AO
authors.lastname: Henriques
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D015398:Signal Transduction; D013171:Spores, Bacterial / Q000254:growth & development*; D013312:Stress, Physiological; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C080950:Spo0A protein, Bacillus subtilis; D014157:Transcription Factors; C075519:rapA protein, Bacillus subtilis; D010749:Phosphoprotein Phosphatases