title: The regulatory mechanism underlying light-inducible production of carotenoids in nonphototrophic bacteria.
abstract: Light is a ubiquitous environmental factor serving as an energy source and external stimulus. Here, I review the conserved molecular mechanism of light-inducible production of carotenoids in three nonphototrophic bacteria: Streptomyces coelicolor A3(2), Thermus thermophilus HB27, and Bacillus megaterium QM B1551. A MerR family transcriptional regulator, LitR, commonly plays a central role in their light-inducible carotenoid production. Genetic and biochemical studies on LitR proteins revealed a conserved function: LitR in complex with adenosyl B12 (AdoB12) has a light-sensitive DNA-binding activity and thus suppresses the expression of the Crt biosynthesis gene cluster. The in vitro DNA-binding and transcription assays showed that the LitR-AdoB12 complex serves as a repressor allowing transcription initiation by RNA polymerase in response to illumination. The existence of novel light-inducible genes and the unique role of the megaplasmid were revealed by the transcriptomic analysis of T. thermophilus. The findings suggest that LitR is a general regulator responsible for the light-inducible carotenoid production in the phylogenetically divergent nonphototrophic bacteria, and that LitR performs diverse physiological functions in bacteria.
authors.affiliation: a Applied Biological Science and Life Science Research Center, College of Bioresource Sciences , Nihon University , Fujisawa , Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takano
mesh_terms: D001410:Bacillus megaterium / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002338:Carotenoids / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D005810:Multigene Family; D010802:Phylogeny; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011401:Promoter Regions, Genetic; D048372:Streptomyces coelicolor / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D016963:Thermus thermophilus / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D014158:Transcription, Genetic; D014805:Vitamin B 12 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; D002338:Carotenoids; D012321:DNA-Directed RNA Polymerases; D014805:Vitamin B 12
keywords: MerR family regulator; carotenoid; nonphototrophic bacteria; vitamin B12