IGEM:Harvard/2006/Brainstorming Papers - Zhipeng
- Kondo T and Ishiura M. . pmid:10649285.
- Kucho K, Okamoto K, Tsuchiya Y, Nomura S, Nango M, Kanehisa M, and Ishiura M. . pmid:15743968.
- Takigawa-Imamura H and Mochizuki A. . pmid:16387328.
- Kutsuna S, Nakahira Y, Katayama M, Ishiura M, and Kondo T. . pmid:16102014.
Kondo et al.
- 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:
- carbohydrate metabolism
- energy metabolism purposes
- Genes mostly:
- 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