Thioredoxin can influence gene expression by affecting gyrase activity

Nucleic Acids Res. 2004 Aug 24;32(15):4563-75. doi: 10.1093/nar/gkh794. Print 2004.


The expression of many genes of facultatively photosynthetic bacteria of the genus Rhodobacter is controlled by the oxygen tension. Among these are the genes of the puf and puc operons, which encode proteins of the photosynthetic apparatus. Previous results revealed that thioredoxins are involved in the regulated expression of these operons, but it remained unsolved as to the mechanisms by which thioredoxins affect puf and puc expression. Here we show that reduced TrxA of Rhodobacter capsulatus and Rhodobacter sphaeroides and oxidized TrxC of R.capsulatus interact with DNA gyrase and alter its DNA supercoiling activity. While TrxA enhances supercoiling, TrxC exerts a negative effect on this activity. Furthermore, inhibition of gyrase activity strongly reduces puf and puc expression. Our results reveal a new signaling pathway by which oxygen can affect the expression of bacterial genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology*
  • Bacteriochlorophylls / biosynthesis
  • DNA Gyrase / metabolism*
  • DNA, Superhelical / metabolism
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation, Bacterial*
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology
  • Mutation
  • Novobiocin / pharmacology
  • Photosynthesis / genetics
  • Rhodobacter / enzymology
  • Rhodobacter / genetics*
  • Rhodobacter / metabolism
  • Rhodobacter capsulatus / enzymology
  • Rhodobacter capsulatus / genetics
  • Rhodobacter capsulatus / metabolism
  • Rhodobacter sphaeroides / enzymology
  • Rhodobacter sphaeroides / genetics
  • Rhodobacter sphaeroides / metabolism
  • Signal Transduction
  • Thioredoxins / genetics
  • Thioredoxins / metabolism*
  • Topoisomerase II Inhibitors
  • Two-Hybrid System Techniques


  • Bacterial Proteins
  • Bacteriochlorophylls
  • DNA, Superhelical
  • Enzyme Inhibitors
  • Membrane Proteins
  • Topoisomerase II Inhibitors
  • Novobiocin
  • Thioredoxins
  • DNA Gyrase