| Project/Area Number |
15370070
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | National Institute of Genetics |
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Principal Investigator |
SHIMAMOTO Nobuo National Institute of Genetics, Structural Biology Center, professor, 構造遺伝学研究センター, 教授 (20127658)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAYAMA Hideki National Institute of Genetics Structural Biology Center, Structural Biology Center, Assistant professor, 構造遺伝学研究センター, 助手 (10370115)
SUSA Motoki National Institute of Genetics Structural Biology Center, Structural Biology Center, Assistant professor, 構造遺伝学研究センター, 助手 (40390629)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2005: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2004: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2003: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | RNA polymerase / promoter / abortive initiation / moribund complex / molecular memory / Branched pathway / GreA / GreB / プロモーター / abortive initiation / moribund複合体 / シンクロブタン / UV損傷 / 転写の分岐反応経路 / シクロブタン / 転写開始 / DNA修復 / コンフォーメーション |
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| Research Abstract |
For several decades, the mechanism of in the early transcription in prokaryotes has been assumed to be a sequence of three essential steps : formation of open complex, initiation of the chemical reaction, and escape of the RNA polymerase from the promoter along with RNA elongation. However, all prokaryotic and eukaryotic RNA polymerases so far isolated have been known to perform "abortive initiation", which is an iterative synthesis and release of oligo-RNA molecules in vitro but its role has not been identified. As a minimal model based on these pioneering works, abortive transcripts were assumed to be unsuccessful precursor of the full-length transcripts, and thus abortive synthesis has been supposed to be a step of the promoter clearance in a sequential model. We examined this hypothesis and found that the major source of abortive transcripts is a complex that cannot produce mature transcript. We named this complex moribund complex and proved that it is formed from a homogeneous pre
… More
paration of RNA polymerase as the productive complex, namely the branched pathway of transcription initiation using the conformations of RNA polymerase promoter complex as a single-molecular memory. We finally proved that this mechanism is working as a regulatory mechanism of transcription initiation in E.coli.
This mechanism has its physiological consequence when the two conformations are irreversible in the time scale of RNA elongation. This is the case of lambda PR and lacUV5 promoters and a reversible cases are found for T7A1 and rrnBP1 promoters. We found GreA and GreB, which have been found as elongation factors, make some promoters more reversible and activate transcription by the net conversion from long-lived moribund complex into rapdly disappearing productive initiation complex. The factors were found to work on the major promoter of atp operon, cspAP1, rpsAP1, rpsAP3, and labbda PR, proving that the branched pathway is working in vivo. The distinct feature of these initiation/elongation factors bind not to DNA but to the minor channel of RNA polymerase as DksA that amplify the action of ppGpp in stringent control. This means the regulation of initiation by controlling the reversibility can compete with the regulation by ppGpp and DksA, finding a cross-talk of two regulatory mechanisms. Less
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