title: Expression of the genes encoding the CasK/R two-component system and the DesA desaturase during Bacillus cereus cold adaptation.
abstract: Two-component systems (TCS) allow a cell to elaborate a variety of adaptive responses to environment changes. The recently discovered CasK/R TCS plays a role in the optimal unsaturation of fatty acids necessary for cold adaptation of the foodborne-pathogen Bacillus cereus Here, we showed that the promoter activity of the operon encoding this TCS was repressed during growth at low temperature in the stationary phase in the parental strain when compared to the casK/R mutant, suggesting that CasR negatively regulates the activity of its own promoter in these conditions. The promoter activity of the desA gene encoding the Δ5 fatty acid desaturase, providing unsaturated fatty acids (UFAs) required for low temperature adaptation, was repressed in the casK/R mutant grown at 12°C versus 37°C. This result suggests that CasK/R activates desA expression during B. cereus growth at low temperature, allowing an optimal unsaturation of the fatty acids. In contrast, desA expression was repressed during the lag phase at low temperature in presence of UFAs, in a CasK/R-independent manner. Our findings confirm that the involvement of this major TCS in B. cereus cold adaptation is linked to the upregulation of a fatty acid desaturase.
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France.
authors.forename: Sara Esther
authors.initials: SE
authors.lastname: Diomandé
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Doublet
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Vasaï
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Guinebretière
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Broussolle
authors.affiliation: SQPOV, INRA, Univ. Avignon, 84000 Avignon, France DGIMI, INRA, Univ. Montpellier, 34095 Montpellier, France julien.brillard@umontpellier.fr.
authors.forename: Julien
authors.initials: J
authors.lastname: Brillard
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D001409:Bacillus cereus / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D003080:Cold Temperature; D003470:Culture Media / Q000737:chemistry; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism / Q000494:pharmacology; D000071677:Histidine Kinase / Q000235:genetics* / Q000378:metabolism
chemical_list: D003470:Culture Media; D005231:Fatty Acids, Unsaturated; D044943:Fatty Acid Desaturases; D000071677:Histidine Kinase
keywords: B. cereus; CasKR; TCS; desaturase; fatty acids; low temperature