The PedR transcriptional regulator interacts with thioredoxin to connect photosynthesis with gene expression in cyanobacteria

Mayumi Horiuchi, Kinu Nakamura, Kouji Kojima, Yoshitaka Nishiyama, Wakako Hatakeyama, Toru Hisabori, Yukako Hihara

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


The redox state of the photosynthetic electron transport chain acts as a critical sensingmechanism by regulating the transcription of key genes involved in the acclimation response to a change in the environment. In the present study we show that the small LuxR-type regulator PedR interacts with Trx (thioredoxin) to achieve photosynthetic electron-transport-dependent transcriptional regulation in the cyanobacterium Synechocystis sp. PCC 6803. TrxM, an isoform of Trx, was isolated as an interacting factor of PedR by pull-down assays. In vitro analysis revealed that the intermolecular disulfide bond formed between Cys80 residues of the PedR homodimer was reduced by both TrxM and TrxX. It has been shown previously that, although PedR is active under low-light conditions, it becomes transiently inactivated following a shift to high-light conditions,with a concomitant conformational change [Nakamura and Hihara (2006) J. Biol. Chem. 281, 36758-36766]. In the present study, we found that the conformational change of PedR and the change in the transcript level of its target gene were minimal when mutants of Synechocystis that lack ferredoxin-Trx reductase or NADPH-Trx reductase were exposed to high levels of light. These results indicate that the reduction of PedR by Trx causes transient inactivation of PedR upon the shift of cyanobacterial cells to high-light conditions.

Original languageEnglish
Pages (from-to)135-140
Number of pages6
JournalBiochemical Journal
Issue number1
Publication statusPublished - 2010 Oct 1
Externally publishedYes


  • Cyanobacterium
  • Light acclimation
  • PedR
  • Redox regulation
  • Synechocystis
  • Thioredoxin

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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