1997 Fiscal Year Final Research Report Summary
Analysis of novel electron-transporting system in DMSO respiration of a photosynthetic bacterium
| Project/Area Number |
08456044
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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 |
応用微生物学・応用生物化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YAMAZAKI Sunao Univ.of Tokyo, Graduate School of Agricultural and Life Sciences dept.of Applied Biochemistry, Professor, 大学院・農学生命科学研究科, 教授 (00011982)
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| Co-Investigator(Kenkyū-buntansha) |
ABO Mitsuru Univ.of Tokyo, Graduate School of Agricultural and Life Sciences dept.of Appl.Bi, 大学院・農学生命科学研究科, 助手 (00272443)
YOSHIMURA Etsuro Univ.of Tokyo, Graduate School of Agricultural and Life Sciences dept.of Appl.Bi, 大学院・農学生命科学研究科, 助教授 (10130303)
OKUBO Akira Univ.of Tokyo, Graduate School of Agricultural and Life Sciences dept.of Appl.Bi, 大学院・農学生命科学研究科, 助教授 (20111479)
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| Project Period (FY) |
1996 – 1997
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| Keywords | DMSO respiration / photodenitrifier / dms operon / dimethyl sulfoxide / tor operon |
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| Research Abstract |
A photodenitrifier, Rhodobacter sphaeroides f.sp. denitrifican, can grow under anaerobic-light condition with dimethyl sulfoxide (DMSO) as the terminal electron acceptor in DMSO respiration. The terminal enzyme of this respiration, dimethyl su1foxide redoctase (DMSOR), was recently seqoenced by our team and analyzed crystallographically by U.S.researchers. Attention was focussed worldwide on the relation between roles of molybdenum-cofactor in active site of the enzyme and this novel DMSO respiration system. This research was therefore organized to clarify the details of this respiration system.
In the upstream of the gene involving DMSO reductase (dmsA), there was two open reading frames composed of dmsB and cmsC.DmsB was suggested to be low molecular weight membrane protein and dmsC was also membraneous and contains pentaheme with molecular weight of 45000. From the comparison of tor operon in E.coil which has high homology with dms operon, dmsC was deduced as a direct electron-transporter to DMSOR.Many trials were done to extress dmsC in E.coli using varieties of operons, dmsA, dmsB, dmsC, dmsBC, and dmsABC.DmsC was expressed as an inclusion body in the cells but no activity was confirmed. The fact that penetaheme was not introduced in the protein molecule seemed to be the limiting factor to express matured proteins.
To elucidate the actual electron flow from dmaC to dmsA, isolation of dmsC from the Rhodobacter cells was performed After many steps of chromatographic purification, dmsC was purified to a single band in SDS-PAGE.Preliminary in-vitro reconstitution experiment, however, showed no activity, indicating that further studies were needed to establish the reconstitution conditions.
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