2004 Fiscal Year Final Research Report Summary
Chemical structure of Yersinia pestis endotoxin and its role in the infection
| Project/Area Number |
14570255
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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 | Kanto Gakuin University (2004)
Kitasato Institute (2002-2003) |
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Principal Investigator |
KAWAHARA Kazuyoshi Kanto Gakuin University, College of Engineering, Professor, 工学部, 教授 (20195126)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUURA Motohiro Jichi Medical School, Medical School, Associate Professor, 医学部, 助教授 (20150089)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Yersinia pestis / Endotoxin / Lipid A / Chemical structure / Growth temperature / Pathogenicity / Acyl transferase / Clonine |
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| Research Abstract |
Mechanism of pathogenicity expressed by Yersinia pestis, which is a strong pathogen for human, has been investigated in relation to the characteristic structure of the endotoxin (LPS). Y.pestis Yreka was grown at 27℃ or 37℃, and the structure was analyzed by mass spectrometry and other chemical methods. At 27℃ it produced the lipid A with C_<120> and C_<16:1> in addition to 3-OH-C_<140> (lipid A-27℃). And the amounts of C_<120> and C_<16:1> were much reduced when grown at 37℃ (lipid A-37℃). Moreover, LPS-37℃ had the core-oligosaccharide with simpler structure than that of LPS-27℃. Next, the ability of these two LPSs to stimulate human and mouse macrophage cells was estimated by measuring TNF induction. LPS-37℃ less stimulated the macrophages than LPS-27℃, and the difference of the activity was larger when human macrophages were used for the assay. These results indicated that Y.pestis synthesizes LPS with less amounts of fatty acids and sugars, which induces lower level of activation of immune system, and such modifications may be one of the mechanisms of the pathogenirity of Y.pestis. In order to investigate the reduction of C_<120> and C_<16:1> in the molecular level, homologues of lipid A acyl transferase genes of E.coli were searched by using database of genome sequences of Y.pestis and its relative species, Y.pseudotuberculosis. As a consequence, two homologous genes of Y.pseudotuberculosis were cloned after PCR amplification in E.coli. Although amino acid sequences of those homologous gene products were identical, modification profiles of fatty acids were different between Y.pestis and Y.pseudotuberculosis. This fact may suggest that the structural modifications are caused by the change of amounts and kinds of fetty acids supplied by biosynthesis, and not by the regulation of gene expression of the acyl transferases.
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