| Project/Area Number |
15590396
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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 |
Bacteriology (including Mycology)
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| Research Institution | Kitasato University |
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Principal Investigator |
SEKIYA Kachiko Kitasato Univ., Sch. of Pharm., Assistant Prof., 薬学部, 講師 (30050579)
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| Co-Investigator(Kenkyū-buntansha) |
ABE Akio Kitasato Univ., Kitasato Institute for Life Sciences, Prof., 北里生命科学研究所, 教授 (50184205)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Streptolysin O / Hemolysis / Electron Microscopy / Negative staining / SLO / cholesterol / Protein-domain / Pore-forming Toxin / ストレプトリジンO / 超微形態 / 分子会合モデル / SLO変異体 / ネガティブ染色 / 分子会合 / リポソーム |
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| Research Abstract |
Streptolysin O (SLO) is a membrane-damaging toxic protein produced by group A streptococci. An ultrastructural analysis of pore formation and the mechanism of hemolysis by SLO, using a mutant form of SLO [SLO(C/A)-SS and native SLO. Electron micrographs of negatively stained preparations revealed that SLO(C/A)-SS was unable to penetrate the erythrocyte membrane as a consequence of immobilization that was due to a disulfide bond between domains. The SLO(C/A)-SS molecules that bound to membranes formed numerous single-layered ring-shaped structures that did not result in pores on the membranes. These structures were similar to the structures formed by native SLO at 0℃. After treatment with dithiothreitol (DTT), SLO(C/A)-SS that had bound to membranes formed double-layered rings with pores on the membranes, as does native SLO at room temperature. There was a correlation between the number of double-layered ring structure with pores that formed and the duration of treatment with DTT. From these results, the following two points were concluded ; (1) Each inner and outer layer of the previously proposed ring model of SLO (J.Bacteriol. 1993) was composed of single SLO molecules associated in a circle. (2) Hemolysis by SLO toxin involves two defined steps; a temperature-independent step and a temperature-dependent step. An increase in temperature is necessary for the occurrence of conformational changes and the formation of the double-layered ring after the insertion of domain 3 into the host cell membrane.
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