title: Bacteriophytochromes: new tools for understanding phytochrome signal transduction.
abstract: The recent discovery of phytochrome-like photoreceptors, collectively called bacteriophytochromes, in a number of bacteria has greatly expanded our understanding of the origins and modes of action of phytochromes in higher plants. These primitive receptors contain an N-terminal domain homologous to the chromophore-binding pocket of phytochromes, and like phytochromes, they bind a variety of bilins to generate photochromic holoproteins. Following the chromophore pocket is a domain similar to two-component histidine kinases, suggesting that these bacterial photoreceptors function in phosphorelay cascades that respond to the light environment. Their organization and distribution support the views that higher-plant phytochromes evolved from a cyanobacterial precursor and that they act as light-regulated kinases. With the ability to exploit bacterial genetics, these bacteriophytochromes now offer simple models to help unravel the biochemical and biophysical events that initiate phytochrome signal transmission.
authors.affiliation: Cellular and Molecular Biology and Genetics Programs and the Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive Madison, WI 53706, USA. vierstra@facstaff.wisc.edu
authors.forename: R D
authors.initials: RD
authors.lastname: Vierstra
authors.forename: S J
authors.initials: SJ
authors.lastname: Davis
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D019143:Evolution, Molecular; D000071677:Histidine Kinase; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D020283:Photoreceptors, Microbial; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D010834:Phytochrome / Q000737:chemistry / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D020283:Photoreceptors, Microbial; D045322:Photosynthetic Reaction Center Complex Proteins; C101088:RcaE protein, cyanobacteria; D010834:Phytochrome; D011494:Protein Kinases; D000071677:Histidine Kinase; C411989:CikA protein, bacteria; C413623:Cph1 phytochrome protein, bacteria; C413659:plpA protein, Synechocystis sp. PCC 6803