RpaB, another response regulator operating circadian clock-dependent transcriptional regulation in Synechococcus elongatus PCC 7942

Mitsumasa Hanaoka, Naoki Takai, Norimune Hosokawa, Masayuki Fujiwara, Yuki Akimoto, Nami Kobori, Hideo Iwasaki, Takao Kondo, Kan Tanaka

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The circadian clock of cyanobacteria is composed of KaiA, KaiB, and KaiC proteins, and the SasA-RpaA two-component system has been implicated in the regulation of one of the output pathways of the clock. In this study, we show that another response regulator that is essential for viability, the RpaA paralog, RpaB, plays a central role in the transcriptional oscillation of clock-regulated genes. In vivo and in vitro analyses revealed that RpaB and not RpaA could specifically bind to the kaiBC promoter, possibly repressing transcription during subjective night. This suggested that binding may be terminated by RpaA to activate gene transcription during subjective day. Moreover, we found that rpoD6 and sigF2, which encode group-2 and group-3 σ factors for RNA polymerase, respectively, were also targets of the RpaAB system, suggesting that a specific group of σ factors can propagate genome-wide transcriptional oscillation. Our findings thus reveal a novel mechanism for a circadian output pathway that is mediated by two paralogous response regulators.

Original languageEnglish
Pages (from-to)26321-26327
Number of pages7
JournalJournal of Biological Chemistry
Volume287
Issue number31
DOIs
Publication statusPublished - 2012 Jul 27

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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