| Project/Area Number |
14370096
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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 |
Bacteriology (including Mycology)
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| Research Institution | Kitasato University |
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Principal Investigator |
INOUE Matsuhisa Kitasato Univ., School of Medicine, Professor, 医学部, 教授 (10008336)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Ryouichi Kitasato Univ., School of Medicine, Assistant Professor, 医学部, 講師 (30224083)
KITASATO Hidero Kitasato Univ., Allied Health Science, Professor, 医療衛生学部, 教授 (90195256)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,000,000 (Direct Cost: ¥14,000,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2003: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Keywords | gram-negative bacteria / class C β-lactamase / regulation of β-lactamase / cephem resistance / permense / amidase / fragment of pepuchidoglyea / muropeptide / AmpCの誘導 / クラスC型酵素 / AmpR / AmpD / AmpG / ムロペプタイド(MuP) / 細胞壁のリサイクル / AmpC / E.cloacae / class C型β-lactamase / セフェムセフェム系薬耐性 / シグナル / 誘導型酵素 / E. cloacae |
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| Research Abstract |
Chromosomally encoded versions of AmpC β-lactamases are particularly importance in clinical isolates of gram-negative bacteria. The molecules that serves as both repressor and the activator of ampC transcription is AmpR. Under without β-lactams, AmpR is present as a repressor by virture of its interaction with a muropeptide. In the setting of high concentrations of cell-wall breakdown product muropeptides, however, muropeptide is displaces AmpR to an activator of ampC transcription. The ease of selection of the AmpR mutations at a frequency of about 10^<-6> strongly suggests that AmpD or AmpR mutants could frequently emerge in the clinical setting. 21 cephem resistant Enterobacter cloacae exhibited AmpC overproduction due to either AmpD or AmpR mutation. E.coli plasmid pKu601 was characterized as having a novel plasmid encoded AmpC enzyme, CFE-1, with an mutation in the ampR gene, in which the Asp at position 135 is changed to Ala. The one point mutant for ampG gene was isolated by examining E.cloacae that expressed low levels of β-lactam constitutively. A single knockout for PBP2 or PBP3 E.cloacae mutants, the data revealed only about a two-fold reduction in AmpC activity to compare with that of wild typw strain.
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