The circadian clock of cyanobacteria

Kondo, Takao; Ishiura, Masahiro

doi:10.1002/(sici)1521-1878(200001)22:1<10::aid-bies4>3.0.co;2-a

Cited by 73 publications

(45 citation statements)

References 50 publications

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“…The strain was then transformed with the promoter trap library (Nakahira et al 2004). Bioluminescent colonies were screened using a cooled CCD camera system (Kondo et al 1994). Among 2.5 × 10 4 Cm-resistant colonies, 342 bright bioluminescent colonies were isolated.…”

Section: Promoter Trap Screeningmentioning

confidence: 99%

Dual KaiC-based oscillations constitute the circadian system of cyanobacteria

Kitayama¹,

Nishiwaki²,

Terauchi³

et al. 2008

Genes Dev.

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122

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In the cyanobacterium Synechococcus elongatus PCC 7942, the KaiA, KaiB, and KaiC proteins are essential for the generation of circadian rhythms. Both in vivo and in vitro, phosphorylation of KaiC is regulated positively by KaiA and negatively by KaiB and shows circadian rhythmicity. The autonomous circadian cycling of KaiC phosphorylation is thought to be the basic pacemaker of the circadian clock and to control genome-wide gene expression in cyanobacteria. In this study, we found that temperature-compensated circadian oscillations of gene expression persisted even when KaiC was arrested in the phosphorylated state due to kaiA overexpression. Moreover, two phosphorylation mutants showed transcriptional oscillation with a long period. In kaiA-overexpressing and phosphorylation-deficient strains, KaiC oscillated and transient overexpression of phosphorylation-deficient kaiC reset the phase of the rhythm. These results suggest that transcription-and translation-based oscillations in KaiC abundance are also important for circadian rhythm generation in cyanobacteria. Furthermore, at low temperature, cyanobacteria can show circadian rhythms only when both the KaiC phosphorylation cycle and the transcription and translation cycle are intact. Our findings indicate that multiple coupled oscillatory systems based on the biochemical properties of KaiC are important to maintain robust and precise circadian rhythms in cyanobacteria.

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Section: Promoter Trap Screeningmentioning

confidence: 99%

Dual KaiC-based oscillations constitute the circadian system of cyanobacteria

Kitayama¹,

Nishiwaki²,

Terauchi³

et al. 2008

Genes Dev.

Self Cite

122

135

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“…17) Thus psbA2 is a good model for analysis of gene expression that is light-responsive and has a circadian rhythm. [18][19][20] The 5 0 -end of the psbA2 transcript was mapped and its promoter sequence, recognized by sigma factors of RNAP, was estimated to be TTTACA (À35 hexamer) and TAGTAT (À10 hexamer), Escherichia coli consensus type sequences recognized by a principal sigma factor, RpoD (Sigma70).…”

Section: A Novel Concept Of Basal Transcription and Light-responsmentioning

confidence: 99%

Regulatory System for Light-Responsive Gene Expression in Photosynthesizing Bacteria:Cis-Elements andTrans-Acting Factors in Transcription and Post-Transcription

Asayama¹

2006

Bioscience, Biotechnology, and Biochemistry

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Cyanobacteria (blue-green algae) are photosynthesizing organisms that can be used as a model for analyzing light-responsive gene expression. The regulatory system of the light-responsive psbA gene with cis-elements and trans-acting factors was studied at both transcriptional and post-transcriptional levels. Positive regulation comprises DNA curvatures (CIT and RIB), upstream elements (UPE and promoter), and a light-induced sigma factor (SigD) of RNA polymerase in transcription. On the other hand, negative regulation involves mRNA instability through an AU-box under darkness. This two-step process is a candidate for a novel mechanism regulating light-responsive gene expression.

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“…Cyanobacteria are the only prokaryotes known so far to exhibit circadian rhythmicity Kondo & Ishiura, 2000). Their circadian system has been comprehensively studied in the unicellular Synechococcus elongatus PCC 7942 (Ditty et al, 2003;Johnson & Golden, 1999).…”

Section: Introductionmentioning

confidence: 99%

Subfamilies of cpmA, a gene involved in circadian output, have different evolutionary histories in cyanobacteria

Dvornyk

2006

Microbiology

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The cpmA gene mediates an output signal in the cyanobacterial circadian system. This gene and its homologues are evolutionarily old, and occur in some non-photosynthetic bacteria and archaea as well as in cyanobacteria. The gene has two functional domains that differ drastically in their level of polymorphism: the N-terminal domain is much more variable than the PurE homologous C-terminal domain. The phylogenetic tree of the cpmA homologues features four main clades (C1–C4), two of which (C1 and C3) belong to cyanobacteria. These cyanobacterial clades match respective ones in the previously reported phylogenetic trees of the other genes involved in the circadian system. The phylogenetic analysis suggested that the C3 subfamily, which comprises the genes from the cyanobacteria with the kaiBC-based circadian system, experienced a lateral transfer, probably from evolutionarily old proteobacteria about 1000 million years ago. The genes of this subfamily have a significantly higher nonsynonymous substitution rate than those of C1 (2·13×10−10 and 1·53×10−10 substitutions per nonsynonymous site per year, respectively). It appears that the functional and selective constraints of the kaiABC-based system have slowed down the rate of sequence evolution compared to the cpmA homologues of the kaiBC-based system. On the other hand, the differences in the mutation rates between the two cyanobacterial clades point to the different functional constraints of the systems with or without kaiA.

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The circadian clock of cyanobacteria

Cited by 73 publications

References 50 publications

Dual KaiC-based oscillations constitute the circadian system of cyanobacteria

Dual KaiC-based oscillations constitute the circadian system of cyanobacteria

Regulatory System for Light-Responsive Gene Expression in Photosynthesizing Bacteria:Cis-Elements andTrans-Acting Factors in Transcription and Post-Transcription

Subfamilies of cpmA, a gene involved in circadian output, have different evolutionary histories in cyanobacteria

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