IGEM:Harvard/2006/Brainstorming Papers - Zhipeng

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  1. Kondo T and Ishiura M. The circadian clock of cyanobacteria. Bioessays. 2000 Jan;22(1):10-5. DOI:10.1002/(SICI)1521-1878(200001)22:1<10::AID-BIES4>3.0.CO;2-A | PubMed ID:10649285 | HubMed [cyano1]
  2. Kucho K, Okamoto K, Tsuchiya Y, Nomura S, Nango M, Kanehisa M, and Ishiura M. Global analysis of circadian expression in the cyanobacterium Synechocystis sp. strain PCC 6803. J Bacteriol. 2005 Mar;187(6):2190-9. DOI:10.1128/JB.187.6.2190-2199.2005 | PubMed ID:15743968 | HubMed [cyano2]
  3. Takigawa-Imamura H and Mochizuki A. Transcriptional autoregulation by phosphorylated and non-phosphorylated KaiC in cyanobacterial circadian rhythms. J Theor Biol. 2006 Jul 21;241(2):178-92. DOI:10.1016/j.jtbi.2005.11.013 | PubMed ID:16387328 | HubMed [cyano3]
  4. Kutsuna S, Nakahira Y, Katayama M, Ishiura M, and Kondo T. Transcriptional regulation of the circadian clock operon kaiBC by upstream regions in cyanobacteria. Mol Microbiol. 2005 Sep;57(5):1474-84. DOI:10.1111/j.1365-2958.2005.04781.x | PubMed ID:16102014 | HubMed [cyano4]
All Medline abstracts: PubMed | HubMed

Kondo et al.

Circadian organization (Kondo et al 2004).
  • gene cluster KaiABC involved
  • no homology to eukarayotic circadian systems
  • Central oscillator controls output patterns; phase of oscillator controlled by input
  • Photosynthesis by day, nitrogen fixation by night (2 incompatible in unicellular)
  • Used luciferase DNA expressed downstream as a reporter
  • Genome 2.7kb in size (e. coli 6.1kb)
  • Put luxAB on a psbA plasmid, luxAB luciferase related protein  volatile
    • See diagram in paper for circuitry
  • KaiABC system
    • Overexpression of KaiC represses KaiA and KaiB
    • Overexpression of KaiA activates KaiBC
    • KaiC center of oscillation
  • Question TBA: why 24h period?
    • Single point mutations in KaiC can change period from 14h to 60h
  • Drosophila and Neurospora also have clock models
  • Cyanobacteria has no nuclear envelope, can divide 6h/time
  • KaiABC analogues only found on archaeobacteria

Kucho et al.

  • Purpose of regulation to prepare cell for night in cyanobacteria
  • Tested Synechocystis, which is a different strain of cyanobacteria
  • 77% in Synechocystis rhymic clones; 100% in Synechococcus
  • In cyanobacteria
    • KaiC regulated by negative feedback autoreg. loop
    • KaiA activates kaiBC
  • Used DNA microarray to determine mRNA cyclic nature
  • cycling genes detected; peak expression from day to night
    • Genes mostly:
      • unassigned
      • carbohydrate metabolism
      • energy metabolism purposes
      • transcription!
      • translation!
  • 2 Sigma factors have circadian rhythm: sll1689, sll0687 on RNAPol


  • (Wikipedia)Cyanobacteria are the only group of organisms that are able to reduce nitrogen and carbon in aerobic conditions