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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacteriochlorophylls / metabolism
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Culture Media
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Escherichia coli / enzymology
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Escherichia coli / genetics
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Gene Expression Regulation, Bacterial
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Light-Harvesting Protein Complexes
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Methionine Sulfoxide Reductases
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Mutation
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Oxidation-Reduction
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Oxidative Stress*
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Oxidoreductases / metabolism
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Oxygen / pharmacology
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Photosynthesis
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Photosynthetic Reaction Center Complex Proteins / genetics
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Photosynthetic Reaction Center Complex Proteins / metabolism
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Rhodobacter capsulatus / enzymology*
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Rhodobacter capsulatus / genetics
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Rhodobacter capsulatus / growth & development
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Rhodobacter capsulatus / physiology
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Thioredoxins / genetics
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Thioredoxins / metabolism*
Substances
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Bacteriochlorophylls
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Culture Media
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Light-Harvesting Protein Complexes
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Membrane Proteins
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Photosynthetic Reaction Center Complex Proteins
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Thioredoxins
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Oxidoreductases
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Methionine Sulfoxide Reductases
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methionine sulfoxide reductase
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Oxygen