| Project/Area Number |
10450308
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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 |
生物・生体工学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
AONO Rikizo Tokyo Institute of Technology, Bioinformation, Prof., 生命理工学部, 教授 (30126643)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1999: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Escherichia coli / solvent tolerance / ArcAB-TolC efflux pump / sox-mar regulon / marA / rob / soxS / MarA / sox-marレギュロン / acrAB / tolC |
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| Research Abstract |
We previously indicated that Escherichia coli acquired cyclohexane tolerance by overexpression of marA, rob or soxS. We certified that the tolerance was enhanced by overproduction of AcrAB-TolC efflux pump encoded by sox-mar regulon genes by the following experiments : 1. Genes belonging to sox-mar regulon were highly expressed in E. coli transformed with one of marA, rob or soxS genes. 2. Cyclohexane-tolerant mutants were defective in the marR gene and showed high levels of MarA. 3. Acta and TolC proteins were highly produced by high expression of the sox-mar regulon genes. 4. Solvent tolerance level of E. coli was decreased extremely by deletion of acrAB operon or tolC gene. The levels of the mutants were not improved by the transformation with marA, rob or soxS. 5. Concomitant high expression of acrAB and tolC improved the solvent tolerance level or E. coli.
E. coli cannot acquire tolerance to more toxic solvent (e.g.. p-xylene) than eyelohexane by the transformation with marA, rob or soxS. From one of the cyclohexane-tolerant mutants, we again isolated a mutant capable of growth on an agar medium overlaid with p-xylene. It was shown that the composition of membrane proteins of the mutant was different from that of the cyclohexane-tolerant mutants used as the parent. Probably, E. coli acquires p-xylene tolerance by an identified mechanism which differed from the cyclohexane tolerance.
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