IGEM:Harvard/2006/Brainstorming Papers - Zhipeng

Cyanobacteria

 * 1) cyano1 pmid=10649285
 * 2) cyano2 pmid=15743968
 * 3) cyano3 pmid=16387328
 * 4) cyano4 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:
 * unassigned
 * carbohydrate metabolism
 * energy metabolism purposes
 * transcription!
 * translation!
 * 2 Sigma factors have circadian rhythm: sll1689, sll0687 on RNAPol

Other

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