2000 Fiscal Year Final Research Report Summary
The mechanism of acquisition of methicillin resistance
| Project/Area Number |
11670272
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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 | JUNTENDO UNIVERSITY |
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Principal Investigator |
ITO Teruyo JUNTENDO UNIVERSITY, Lecturer, 医学部, 講師 (10095763)
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| Project Period (FY) |
1999 – 2000
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| Keywords | MRSA (methicillin-resistant Staphylococcus aureus) / mecA / PBP2 / SCCmec(staphylococcal cassette chromosome mec) / excision / integration / ccrA, B (cassette chromosome recombinase A, B) / mobile genetic element |
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| Research Abstract |
(1) Cloning and determination of three types of SCCmec.
beta-lactam resistance gene mecA of Staphylococcus aureus is carried by a nova mobile genetic element, designated staphylococcal cassette chromosome mec(SCCmec)
We have cloned and determined the nucleotide sequence of SCCmecs of three strains, NCTC10442(isolated in England in 1961), N315(isolated in Japan in 1982), and 85/2082 (isolatd in New Zieland in 1985). There were substantial differences in the size and nucleotide sequences between the elements and the SCCmec. Structural analysis of the new elements revealed that they possessed all the salient features of the SCCmec ; conserved terminal inverted repeats and direct repeats at the integration junction points ; conserved genetic organization around mecA gene ; and the presence of cassette chromosome recombinase(ccr) genes responsible for the movement of SCCmec.
(2) Mobility of SCCmec.
We have identified two movel genes, ccrA and ccrB, encoding polypeptides having a partial homology to recombinases of the invertase/resolvase family. The open reading frames were found to catalyze precise excision of the SCCmec from the methicillin-resistant S.aureus chromosome and site-specific as well as orientation-specific integration of the SCCmec into the S.aureus chromosome when introduced into the cells as a recombinant multicopy plasmid.
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[Publications] Ito, T., Katayama, Y., Asada, K., Mori, N., Tsutsumimoto, K., Tiensasitorn, C., and Hiramatsu, K.: "Complete structure of three types of staphylococcus cassette chromosome mec(SCCmec)ingegrated in the chromosome of MRSA strains in the world."Antimiclobial Agents and Chemotherapy. (in press).
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