2007 Fiscal Year Final Research Report Summary
Temporal integration of cellular system by circadian clock in cyanobacteria
| Project/Area Number |
15GS0308
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| Research Category |
Grant-in-Aid for Creative Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Institution | Nagoya University |
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Principal Investigator |
KONDO Takao Nagoya University, Faculty of Science, Professor (10124223)
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| Co-Investigator(Kenkyū-buntansha) |
IWASAKI Hideo Waseda University, Faculty of Science and Engineering, Associate Profassor (00324393)
OYAMA Tokitaka Nagoya University, Faculty of Science, Assistant Professor (30324396)
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| Project Period (FY) |
2003 – 2007
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| Keywords | circadian clock / cyanobacteria / clock protein / ATPase / KaiC |
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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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[Journal Article] Role of KaiC phosphorylation in the circadian clock system of Synechococcus elongatus PCC 79422004
Author(s)
Nishiwaki T, Satomi Y, Nakajima M, Lee C, Kiyohara R, Kageyama H, Kitayama Y, Temamoto M, Yamaguchi A, Hijikata A, Go M, Iwasaki H, Takao T., T.Kondo
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Journal Title
Proc.Natl.Acad.Sci. 101
Pages: 13927-13932
Description
「研究成果報告書概要(和文)」より
Peer Reviewed
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[Presentation] Synchronization of a circadian clock in vitro2007
Author(s)
伊藤浩史, 景山伯春, 陸田径典, 小山時隆, 近藤孝男
Organizer
The Joint Annual Meetings of the Society for Mathematical Biology and the Japanese Society for Mathematical Biology
Place of Presentation
San Jose, USA
Year and Date
20070731-20070803
Description
「研究成果報告書概要(和文)」より
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