title: Photo-induced regulation of the chromatic adaptive gene expression by Anabaena sensory rhodopsin.
abstract: Rhodopsin molecules are photochemically reactive membrane-embedded proteins, with seven transmembrane α-helices, which bind the chromophore retinal (vitamin A aldehyde). They are roughly divided into two groups according to their basic functions: (i) ion transporters such as proton pumps, chloride pumps, and cation channels; and (ii) photo-sensors such as sensory rhodopsin from microbes and visual pigments from animals. Anabaena sensory rhodopsin (ASR), found in 2003 in the cyanobacterium Anabaena PCC7120, is categorized as a microbial sensory rhodopsin. To investigate the function of ASR in vivo, ASR and the promoter sequence of the pigment protein phycocyanin were co-introduced into Escherichia coli cells with the reporter gene crp. The result clearly showed that ASR functions as a repressor of the CRP protein expression and that this is fully inhibited by the light activation of ASR, suggesting that ASR would directly regulate the transcription of crp. The repression is also clearly inhibited by the truncation of the C-terminal region of ASR, or mutations on the C-terminal Arg residues, indicating the functional importance of the C-terminal region. Thus, our results demonstrate a novel function of rhodopsin molecules and raise the possibility that the membrane-spanning protein ASR could work as a transcriptional factor. In the future, the ASR activity could be utilized as a tool for arbitrary protein expression in vivo regulated by visible light.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Irieda
authors.forename: Teppei
authors.initials: T
authors.lastname: Morita
authors.forename: Kimika
authors.initials: K
authors.lastname: Maki
authors.forename: Michio
authors.initials: M
authors.lastname: Homma
authors.forename: Hiroji
authors.initials: H
authors.lastname: Aiba
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sudo
mesh_terms: D017033:Anabaena; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology / Q000528:radiation effects*; D008027:Light; D009154:Mutation; D010798:Phycocyanin / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology*; D017434:Protein Structure, Tertiary; D025604:Rhodopsins, Microbial / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D025604:Rhodopsins, Microbial; D010798:Phycocyanin