2003 Fiscal Year Final Research Report Summary
Elucidation of basic principle in genetic information translation system by using the specialty of animal mitochondria
| Project/Area Number |
14208077
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
WATANABE Kimitsuna The University of Tokyo, Graduate School of Frontier Sciences, Professor, 大学院・新領域創成科学研究科, 教授 (00134502)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Tsutomu The University of Tokyo, Graduate School of Frontier Sciences, Lecturer, 大学院・新領域創成科学研究科, 講師 (20292782)
OHTSUKI Takashi The University of Okayama, Department of Engineering, Lecturer, 工学部, 講師 (80321735)
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| Project Period (FY) |
2002 – 2003
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| Keywords | mitochondria / tRNA / translation system / minimal prerequisite structure / ribosome / rRNA / EF-G / L7 / L12 protein |
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| Research Abstract |
The aim of this project is to elucidate the basic principle in genetic information translation system by using the specialty of animal mitochondria. This can be done by combining the well-studied E.coli translation system with the special translation system of animal mitochondria. (1)The minimal prerequisite structure of tRNA : The higher-order structure of nematode mitochondrial (mt) tRNA^<Ser>_<UCU>, which is the smallest tRNA in the extant organisms (54 nucleotides, having no D arm and small T arm consisting of 3 base pairs and a loop with 4 bases), was examined by using NMR. It turned out that almost all the base-pairs predicted from its clover-leaf structure existed in solution and the connector region consisting of the truncated D loop and extra loop had a rather flexible structure. This mobility is indispensable for the tRNA^<Ser>_<UCU> to maintain the relative arrangement of the 3'-terminus and the anticodon equal to that of the usual tRNAs. (2)The minimal prerequisite structur
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e of ribosome : In the animal mt ribosome, the content of rRNA is about a half, but that of proteins is doubled, as compared with the counterparts of E.coli ribosome. The functional regions of mt rRNA are strictly conserved in the central parts of two ribosomal subunits and the peripheral regions of rRNA lacking in the mt ribosome are embedded by proteins so as to maintain the whole shapes of ribosomes almost equal between mt and E.coli. It turned out that some of the stem/loop structures in the peripheral regions of mt ribosome are dispensable. (3)What is the trigger in the hydrolysis reaction of GTP which is an energy source in the translation system : It was suggested that the trigger in the hydrolysis reaction of GTP is L7/L12 protein in 50S ribosomal subunit, on the basis of the fact that GTPase activity of EF-G is activated by L7/L12. We have confirmed this proposal by elucidating that E.coli EF-G can function on the mt ribosome in which only the L7/L12 protein is replaced by the counterpart of E.coli ribosome, although E.coli EF-G cannot work on the native mt ribosome. Less
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