title: Bacteriophytochrome-dependent regulation of light-harvesting complexes in Rhodopseudomonas palustris anaerobic cultures.
abstract: Bacteriophytochromes (Bphs) are photoreceptors that help bacteria sense changes in light wavelength and intensity. Bphs contain a linear tetrapyrrole chromophore that, upon absorption of red or far-red light, undergoes a cis-trans isomerization that leads to a conformational change in the holoprotein. The conformation and type of Bph affects the expression of genes. The linear tetrapyrrole bound by Bphs is thought to come from O(2)-dependent cleavage of heme by a heme oxygenase. We have discovered that the absence of O(2) does not inhibit the normal function of two Bphs in the regulation of Rhodopseudomonas palustris light-harvesting complexes. These observations imply that: (i) a linear tetrapyrrole can be made anaerobically, either through anaerobic heme cleavage by a novel enzyme or directly from the heme precursor hydroxymethylbilane without ring cleavage; or (ii) that Bph-dependent signal transduction does not require a chromophore.
authors.affiliation: Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Stephan
authors.initials: S
authors.lastname: Noll
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Beatty
mesh_terms: D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D020283:Photoreceptors, Microbial / Q000737:chemistry / Q000378:metabolism*; D010834:Phytochrome / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D012241:Rhodopseudomonas / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012926:Social Control, Formal; D045725:Tetrapyrroles / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D020283:Photoreceptors, Microbial; D045725:Tetrapyrroles; D010834:Phytochrome; D006419:Heme Oxygenase (Decyclizing)