IGEM:Harvard/2006/Brainstorming Papers - Hetmann
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- Nakajima M, Imai K, Ito H, Nishiwaki T, Murayama Y, Iwasaki H, Oyama T, and Kondo T. . pmid:15831759.
- Imai K, Nishiwaki T, Kondo T, and Iwasaki H. . pmid:15229218.
- Naef F. . pmid:16729054.
Nakajima et. al
- cyanobacterium Synechococcus elongatus (PCC 7942)
- three genes components (kaiA, kaiB, and kaiC)
- Kai proteins regulate the kaiBC operon
- Oscillation of KaiC phosphorylation cycle is the pacemaker, molecular timer
- KaiA enhances KaiC autophosphorylation
- KaiB attenuates the effect of KaiA
- Oscillation of KaiC phosphorylation maybe generated by KaiA and KaiB cooperation
- Nakajima et. al incubated recombinant KaiC protein with KaiA and KaiB at a ratio similar to in vivo to test it in vitro
- KaiC phosphorylation oscillated robustly without damping
- KaiC not degraded during the reaction
- Oscillation of KaiC phosphorylation is autonomous due to cooperation of three Kai proteins
- The thermal sensitivity in vitro same as in vivo gene expression rhythm
- They found that KaiC phosphorylation is the molecular timer for the circadian rhythm of Synechococcus
- KaiC hexamer may have many phosphorylation states with different biochemical characteristics
- In addition, the reaction rate of KaiC phosphorylation and dephosphorylation are slow reducing the energy needed