MISC

2006年8月

Expression of the circadian clock-related gene pex in Cyanobacteria increases in darkness and is required to delay the clock

JOURNAL OF BIOLOGICAL RHYTHMS
  • Naoki Takai
  • ,
  • Shingo Ikeuchi
  • ,
  • Katsushi Manabe
  • ,
  • Shinsuke Kutsuna

21
4
開始ページ
235
終了ページ
244
記述言語
英語
掲載種別
DOI
10.1177/0748730406289400
出版者・発行元
SAGE PUBLICATIONS INC

The time measurement system of the unicellular cyanobacterium Synechococcus elongatus PCC 7942 is analogous to the circadian clock of eukaryotic cells. Circadian clock-related genes have been identified in this strain. The clock-related gene pex is thought to maintain the normal clock period because constitutive transcription or deficiency of this gene causes respectively longer (similar to 28 h) or shorter (similar to 24 h) circadian periods than that of the wild type (similar to 25 h). Here, the authors report other properties of pex in the circadian system. Levels of pex mRNA increased significantly in a 12-h exposure to darkness. Western blotting with a GST-Pex antibody revealed a 13.5-kDa protein band in wildtype cells that were incubated in the dark, while this protein was not detected in pex-deficient mutant cells. Therefore, the molecular weight of the Pex protein appears to be 13.5 kDa in vivo. The PadR domain, which is conserved among DNA-binding transcription factors in lactobacilli, was found in Pex. In the pex mutant, several 12-h light/12-h dark cycles reset the phase of the clock by 3 h earlier (phase advance) compared to wild-type cells. The degree of the advance in the pex mutant was proportional to the number of exposed light-dark cycles. In addition, ectopic induction of pex with an inducible Escherichia coli promoter, Ptrc, delayed the phase in the examined recombinant cells by 2.5 h (phase delay) compared to control cells. These results suggest that the dark-responsive gene expression of pex delays the circadian clock under daily light-dark cycles.

Web of Science ® 被引用回数 : 19

リンク情報
DOI
https://doi.org/10.1177/0748730406289400
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/16864644
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000239244600001&DestApp=WOS_CPL