The Bacillus subtilis SinR and RapA developmental regulators are responsible for inhibition of spore development by alcohol.
Even though there is a large body of information concerning the harmful effects of alcohol on different organisms, the mechanism(s) that affects developmental programs, at a single-cell level, has not been clearly identified. In this respect, the spore-forming bacterium Bacillus subtilis constitutes an excellent model to study universal questions of cell fate, cell differentiation, and morphogenesis. Here, we demonstrate that treatment with subinhibitory concentrations of alcohol that did not affect vegetative growth inhibited the initiation of spore development through a selective blockage of key developmental genes under the control of the master transcription factor Spo0A approximately P. Isopropyl-beta-D-thiogalactopyranoside-directed expression of a phosphorylation-independent form of Spo0A (Sad67) and the use of an in vivo mini-Tn10 insertional library permitted the identification of the developmental SinR repressor and RapA phosphatase as the effectors that mediated the inhibitory effect of alcohol on spore morphogenesis. A double rapA sinR mutant strain was completely resistant to the inhibitory effects of different-C-length alcohols on sporulation, indicating that the two cell fate determinants were the main or unique regulators responsible for the spo0 phenotype of wild-type cells in the presence of alcohol. Furthermore, treatment with alcohol produced a significant induction of rapA and sinR, while the stationary-phase induction of sinI, which codes for a SinR inhibitor, was completely turned off by alcohol. As a result, a dramatic repression of spo0A and the genes under its control occurred soon after alcohol addition, inhibiting the onset of sporulation and permitting the evaluation of alternative pathways required for cellular survival.
Gottig
Natalia
N
Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Instituto de Biología Molecular y Celular de Rosario, IBR-CONICET, Suipacha 531, Rosario (2000), Argentina.
Pedrido
María Eugenia
ME
Méndez
Marcelo
M
Lombardía
Esteban
E
Rovetto
Adrián
A
Philippe
Valeria
V
Orsaria
Lelia
L
Grau
Roberto
R
D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000502:physiology*; D000431:Ethanol / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D010749:Phosphoprotein Phosphatases / Q000502:physiology*; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D014157:Transcription Factors
D001426:Bacterial Proteins; C080950:Spo0A protein, Bacillus subtilis; D014157:Transcription Factors; C075519:rapA protein, Bacillus subtilis; C076733:FlaD protein, Bacteria; D000431:Ethanol; D010749:Phosphoprotein Phosphatases