| Project/Area Number |
60580149
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
代謝生物化学
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| Research Institution | Nagoya University, Faculty of Science |
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Principal Investigator |
MUTO Akira Nagoya University, Faculty of Science , Associate Professor, 理学部, 助教授 (80034635)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAO Fumiaki Nagoya University, Faculty of Science , Reseach Associate, 理学部, 助手 (10158074)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | mycoplasma / genetic code / stop codon / tryptophane tRNA / ribosomal protein / クローニング / 変異圧 |
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| Research Abstract |
The codon UGA, one of the translational stop signals in the "universal genetic code", is read as tryptophane in Mycoplasma capricolum (Yamao et al., 1985). This finding is based on the following observations. (1) The DNA sequence of the cloned ribosomal protein gene cluster of M. capricolum revealed that many UGA appeared in the reading frames. In most cases, the UGAs appeared at the position of tryptophane in the corresponding Escherichia coli ribosomal proteins. (2) No UGA is so far found to be used as a stop codon in M. capricolum. (3) M. capricolum contains two <tRNA^(Trp)> : one of which has an anticodon UCA corresponding to the codon UGA, and the other has CCA for universal tryptophane codon UGG.
Several observations indicated that UGA is the predominant codon for tryptophane and UGG is rarely used in M. capricolum.
The guanine and cytosine (G + C) content of Mycoplasma DNA is extremely low (about 25%). The change of the UGA codon assignment in this bacterium might be brought about by the biased mutation pressure replaceing GC-pairs by AT-pairs that had been exerted on the mycoplasma genomic DNA during evolution.
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