Thioredoxin 2 is involved in oxidative stress defence and redox-dependent expression of photosynthesis genes in Rhodobacter capsulatus

Microbiology (Reading). 2003 Feb;149(Pt 2):419-430. doi: 10.1099/mic.0.25978-0.


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

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriochlorophylls / metabolism
  • Culture Media
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Gene Expression Regulation, Bacterial
  • Light-Harvesting Protein Complexes
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Methionine Sulfoxide Reductases
  • Mutation
  • Oxidation-Reduction
  • Oxidative Stress*
  • Oxidoreductases / metabolism
  • Oxygen / pharmacology
  • Photosynthesis
  • Photosynthetic Reaction Center Complex Proteins / genetics
  • Photosynthetic Reaction Center Complex Proteins / metabolism
  • Rhodobacter capsulatus / enzymology*
  • Rhodobacter capsulatus / genetics
  • Rhodobacter capsulatus / growth & development
  • Rhodobacter capsulatus / physiology
  • Thioredoxins / genetics
  • Thioredoxins / metabolism*


  • Bacteriochlorophylls
  • Culture Media
  • Light-Harvesting Protein Complexes
  • Membrane Proteins
  • Photosynthetic Reaction Center Complex Proteins
  • Thioredoxins
  • Oxidoreductases
  • Methionine Sulfoxide Reductases
  • methionine sulfoxide reductase
  • Oxygen