title: Bacteriochlorophyll-dependent expression of genes for pigment-binding proteins in Rhodobacter capsulatus involves the RegB/RegA two-component system.
abstract: Expression of the puf and puc operons, which encode proteins of the photosynthetic apparatus of Rhodobacter capsulatus, is regulated by oxygen. A drop in the oxygen tension in the environment leads to an increase in the levels of puf and puc mRNAs. In strains lacking bacteriochlorophyll (Bchl) due to mutations in bch genes, the rise in puf and puc mRNA levels observed on reduction of oxygen tension is much less pronounced than in wild-type cells, indicating co-regulation of the syntheses of pigments and pigment-binding proteins. Here we show that Bchl synthesis also affects the expression of the bchC gene, which codes for a subunit of bacteriochlorophyll synthase, suggesting an autoregulatory mechanism for the Bchl biosynthetic pathway. Furthermore, our data provide evidence that the RegB/RegA two-component system, which is known to play a central role in oxygen-controlled expression of photosynthesis genes, is also involved in the Bchl-dependent regulation. Mutant strains which do not synthesize RegB or RegA show similar oxygen-dependent puf and puc expression in the presence and absence of Bchl. Our results support the view that the RegB/RegA system can directly or indirectly sense whether Bchl synthesis takes place or not.
authors.affiliation: Institut für Mikrobiologie und Molekularbiologie, Universität Giessen, Heinrich-Buff-Ring 26-32, Germany.
authors.forename: E M
authors.initials: EM
authors.lastname: Abada
authors.forename: A
authors.initials: A
authors.lastname: Balzer
authors.forename: A
authors.initials: A
authors.lastname: Jäger
authors.forename: G
authors.initials: G
authors.lastname: Klug
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001429:Bacteriochlorophylls / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D019729:Carbon-Oxygen Ligases / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011494:Protein Kinases; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; C107183:CrtJ protein, Rhodobacter; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; C091084:RegA protein, Rhodobacter; C091081:RegB protein, Rhodobacter; D015534:Trans-Activators; D014157:Transcription Factors; D011494:Protein Kinases; D019729:Carbon-Oxygen Ligases; C105512:bacteriochlorophyll a synthase; D010100:Oxygen