| Budget Amount *help |
¥413,010,000 (Direct Cost: ¥317,700,000、Indirect Cost: ¥95,310,000)
Fiscal Year 2007: ¥70,720,000 (Direct Cost: ¥54,400,000、Indirect Cost: ¥16,320,000)
Fiscal Year 2006: ¥74,100,000 (Direct Cost: ¥57,000,000、Indirect Cost: ¥17,100,000)
Fiscal Year 2005: ¥80,210,000 (Direct Cost: ¥61,700,000、Indirect Cost: ¥18,510,000)
Fiscal Year 2004: ¥105,300,000 (Direct Cost: ¥81,000,000、Indirect Cost: ¥24,300,000)
Fiscal Year 2003: ¥82,680,000 (Direct Cost: ¥63,600,000、Indirect Cost: ¥19,080,000)
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| Research Abstract |
In the cyanobacterium, Synechococcus elongatus PCC 7942, three genes (kaiA, kaiB and kaiC) code essential components of the circadian clock, and negative feedback regulation of kaiBC expression by Kai proteins was confirmed and proposed as a core loop of prokaryotic circadian oscillator. However, it would be difficult to explain the key feature of circadian oscillation, that is, about 24-hour periodicity and its stability, by the feedback model of clock gene expression. To address this question, we developed DNA-chips and bioluminescence reporter strain for all transcripts and elucidated basic feature of global regulation of transcription by Kai proteins.
Recently, by studying kaiC phosphorylation in continuous darkm conditions, we found robust circadian cycling of kaiC phosphorylation even without kaiBC mRNA accumulation. Moreover, by incubating kaiC with kaiA, kaiB, and ATP, we found the self-sustainable circadian oscillation of kaiC phosphorylation. The in vitro oscillation of kaiC phosphorylation persisted for at least three cycles and the period was compensated against temperature change. These results demonstrate that the oscillation of kaiC phosphorylation is the primary pacemaker of the cyanobacterial circadian clock. We further analyzed the in vitro kaiC phosphorylation cycle and found that extraordinarily weak (16 ATP/day/kaiC) but temperature-compensated ATPase activity of kaiC is a key reaction in defining the circadian period.
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