1999 Fiscal Year Final Research Report Summary
The role of translation releasing factor on codon recognition
| Project/Area Number |
10044335
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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 |
Biological pharmacy
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| Research Institution | National Cancer Center Research Institution |
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Principal Investigator |
KUCHINO Yoshiyuki Nat. Cancer Cent. Res. Inst., Biophysics Division, Chief, 研究所・生物物理部, 部長 (60124418)
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| Co-Investigator(Kenkyū-buntansha) |
MURAMATSU Tomonari Nat. Cancer Cent. Res. Inst., Biophysics Div., Section Chief, 研究所・生物物理部, 室長 (70212256)
KLAUS Heckmann Univ.of Munster, Inst.of Zoology, 教授
HIKDBERG Beier Univ, of Wurzburg・ Inst・of Biochemic, 助教授
HECKMANN Klaus Univ. of Munster, Inst. of Zoology, Professor
BEIER Hildberg Univ. of Wurzburg, Inst. for Biochemie, Assoc. Prof.
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| Project Period (FY) |
1998 – 1999
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| Keywords | polypeptide release factor / genetic code / termination codon / ciliates / Tetrahymena / Euplotes |
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| Research Abstract |
Termination of protein biosynthesis and release of the nascent polypeptide chain takes place as a response to an in-frame stop codon in the aminoacyl (A) site of the ribosome. This process is mediated by two classes of polypeptide release factors (RFs) and GTP. Class-I RFs recognize the termination codons and class-II RFs mediate GTP hydrolysis. It has been postulated that eukaryotic RF 1 (eRF 1) functions as an omnipotent release factor, decoding all three stop codons. However, as we reported previously, ciliates have reassigned stop codons as sense codons in the course of evolution different from most of other eukaryotes. For example, in a number of ciliates such as Tetrahymena and Paramecium, UAG and UAA codons encode glutamine and only UGA is used as a stop codon. On the other hand, in Euplotes, UGA encodes cysteine and UAA is used as the main stop codon and only rarely UAG is used. Thus, we believe that investigating the structure and function of ciliate eRFs having the different specificity in stop codon recognition from other eukaryotic eRFs might be important to understand the molecular mechanism of termination of protein biosynthesis in eukaryotes and the mechanism of evolution of the genetic code. With the aim to look for differences between ciliate eRFs and other eukaryote release factors, we amplified macronuclear DNA of Tetrahymena and Euplotes with help of primers specific for conserved regions of eukaryotic class-I release factors reported so far. We succeeded in isolation of one and two genes encoding eRF1 from Tetrahymena and Euplotes, respectively. We analyzed the primary structures of eRF1s isolated from these ciliates and compared them with those of other eukaryotic release factors. Based on the changes of the amino acid sequence in the region proposed as the codon recognition site in human eRF1 whose crystal structure has been analysed, we predicted the amino acids participating in stop codon recognition in eRF1 release factor.
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