title: A role of Anabaena sensory rhodopsin transducer (ASRT) in photosensory transduction.
abstract: In 2003, Anabaena sensory rhodopsin (ASR), a membrane-bound light sensor protein, was discovered in cyanobacteria. Since then, a large number of functions have been described for ASR, based on protein biochemical and biophysical studies. However, no study has determined the in vivo mechanism of photosensory transduction for ASR and its transducer protein (ASRT). Here, we aimed to determine the role of ASRT in physiological photo-regulation. ASRT is known to be related to photochromism, because it regulates the expression of phycocyanin (cpc-gene) and phycoerythrocyanin (pec gene), two major proteins of the phycobilisome in cyanobacteria. By examining wild type and knockout mutant Anabaena cells, we showed that ASRT repressed the expression of these two genes. We also demonstrated physical interactions between ASRT, ASR, and the promoter regions of cpc, pec, kaiABC (circadian clock gene) and the asr operon, both in vitro and in vivo. Binding assays indicated that ASRT had different sites of interaction for binding to ASR and DNA promoter regions. ASRT also influenced the retinal re-isomerization rate in dark through a physical interaction with ASR, and it regulated reporter gene expression in vivo. These results suggested that ASRT relayed the photosignal from ASR and directly regulated gene expression.
authors.affiliation: Department of Life Science and Institute of Biological Interfaces, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul, 121-742, Korea.
authors.forename: So Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Sa Ryong
authors.initials: SR
authors.lastname: Yoon
authors.forename: SongI
authors.initials: S
authors.lastname: Han
authors.forename: Yuna
authors.initials: Y
authors.lastname: Yun
authors.forename: Kwang-Hwan
authors.initials: KH
authors.lastname: Jung
mesh_terms: D017033:Anabaena / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D007536:Isomerism; D008027:Light; D055537:Light Signal Transduction; D008565:Membrane Proteins / Q000378:metabolism; D009876:Operon; D052980:Phycobilins / Q000235:genetics*; D045524:Phycobilisomes / Q000378:metabolism; D010798:Phycocyanin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D055503:Protein Multimerization; D025603:Sensory Rhodopsins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D052980:Phycobilins; D045524:Phycobilisomes; D025603:Sensory Rhodopsins; C038397:phycoerythrocyanin; D010798:Phycocyanin