title: Enhancement of a sigma(B)-dependent stress response in Bacillus subtilis by light via YtvA photoreceptor.
abstract: YtvA of Bacillus subtilis consists of light, oxygen or voltage (LOV) domain and sulfate transporter and anti-sigma antagonist (STAS) domain, and was reported to act as a photoreceptor, sensing light signals through the LOV domain, like a plant blue light receptor, phototropin. At the same time, YtvA was reported to act as a positive regulator for stress responsive-gene expression regulated by sigma(B) factor. Here we indicate that, like phototropins, the conserved Cys residue among the LOV domains is required for light-sensing in YtvA in vitro, possibly by the photoadduct formation, and YtvA forms a homodimer via its LOV domain, independently to light signal. We also indicate that, when ytvA expression is in normal level, light itself does not trigger sigma(B) activation, but a photo-enhancement of sigma(B) activity, activated by salt stress, occurs only in the presence of ytvA. The conserved Cys residue in the LOV domain and the STAS domain seem to be responsible for light-sensing and signal-transmission to the sigma(B) regulatory network, respectively.
authors.affiliation: Division of Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Suzuki
authors.forename: Naoki
authors.initials: N
authors.lastname: Takaya
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hoshino
authors.forename: Akira
authors.initials: A
authors.lastname: Nakamura
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology* / Q000528:radiation effects; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D010777:Photochemistry; D017434:Protein Structure, Tertiary / Q000235:genetics; D012492:Salts; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012492:Salts; C079011:SigB protein, Bacteria; D012808:Sigma Factor