title: Thioredoxin 2 is involved in oxidative stress defence and redox-dependent expression of photosynthesis genes in Rhodobacter capsulatus.
abstract: Thioredoxins are small ubiquitous proteins that display different functions mainly via redox-mediated processes. The facultatively photosynthetic bacterium Rhodobacter capsulatus harbours at least two genes for thioredoxin 1 and 2, trxA and trxC. It is demonstrated that thioredoxin 2 of R. capsulatus can partially replace the thioredoxin 1 function as a hydrogen donor for methionine sulfoxide reductase but cannot replace thioredoxin 1 as a subunit of phage T7 DNA polymerase. By inactivating the trxC gene in R. capsulatus, it is shown that thioredoxin 2 is involved in resistance against oxidative stress. As thioredoxin 1 of Rhodobacter sphaeroides, R. capsulatus thioredoxin 2 affects the oxygen-dependent expression of photosynthesis genes, albeit in an opposite way. The trxC mutant of R. capsulatus shows a stronger increase in photosynthesis gene expression after a decrease in oxygen tension than the isogenic wild-type strain. The expression of the trxC gene is downregulated by oxygen.
authors.affiliation: Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
authors.forename: Kuanyu
authors.initials: K
authors.lastname: Li
authors.affiliation: Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Härtig
authors.affiliation: Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Klug
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051150:Methionine Sulfoxide Reductases; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001429:Bacteriochlorophylls; D003470:Culture Media; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D013879:Thioredoxins; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; D010100:Oxygen