| Project/Area Number |
17580071
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied microbiology
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| Research Institution | Tokyo University of Agriculture |
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Principal Investigator |
YOSHIKAWA Hirofumi Tokyo University of Agriculture, Bioscience, Professor, 応用生物科学部, 教授 (50175676)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | DNA replication / DNA polymerase I / Okazaki fragment / RNase H / Essential paralog / Synthetic lethal / Bacillus subtilis / Molecular genetics |
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| Research Abstract |
A major factor in removing RNA primers during the processing of Okazaki fragments is DNA polymerase I (Pol I). Pol I is thought to remove the RNA primers and fill the resulting gaps simultaneously. RNase H encoded by rnh genes is another factor in removing the RNA primers and previous studies disagreed with respect to the essentiality of both polA and rnh genes. Our study that looked for the synthetic lethality of paralogs in Bacillus subtilis detected several essential functions of doublet paralogs including the polA and ypcP pair. YpcP consists of only the 5'-3' exonuclease domain. On the other hand, there are 4 genes encoding RNase H in the B. subtilis genome. In the current study we first confirmed that the polA genes of both Escherichia coli and B. subtilis could be completely deleted. We found that the 5'-3' exonuclease activity was indispensable in B. subtilis and E. coli and in the cyanobacterial strain, suggesting that the essential function is common to all organisms. Finally, we succeeded in constructing a B. subtilis strain that lacked all RNase H genes, indicating that the enzymatic activity is dispensable at least in the wild type. Increasing the 5'-3' exonuclease activity partially compensated for a defective phenotype of RNase H, suggesting cooperative functions for both enzyme systems. Our search for the distribution of the 5'-3' exonuclease domain among 250 bacterial genomes resulted in the finding that all eubacteria, but not archaea, possess this domain.
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