Full-Text Search:
Home|About CNKI|User Service|中文
Add to Favorite Get Latest Update

Specific mutations of ampD gene leading to the emergence of derepressed high-production of AmpC β-lactamase

TU Wan,ZHAO Hu.Department of Clinical Laboratory,Huadong Hospital of Fudan University,Shanghai 200040,China  
Objective To reveal the influence factor of ampD specific mutation on the transformation of AmpCβ-lactamase from non-high-productive type to derepressed the high-productive type in Enterobacter cloacae.Methods The selected chromatin-mediated derepressed high-productive strains of Enterobacter cloacae and genomic DNA were extracted,and genomic ampD was amplified by using PCR,and then sequenced and confirmed by specific mutation.Use site-directed mutagenesis to mutate the wild-type Enterobacter cloacae for the above site.The changes of AmpCβ-lactamase types were detected by the improved Cefotaxime three-dimensional test.Results Of the 121 strains of Enterobacter cloacae,15 strains were chromatin-mediated derepressed high-productive type,8 strains had significant mutations and 7 strains of site-directed mutagenesis were established.Ecl MAC274 inserting A)、Ecl MC(327 missing C)and Ecl MF(27 inserting G)were changed from non-high-productive type to derepressed-high-productive type,but Ecl MB(371 inserting T),Ecl MD(515 missing C),Ecl ME(324 C→A),Ecl MG(238C→A 302T→A)did not change in AmpCβ-lactamase types.Conclusion The significant mutations that could lead to the transformation of AmpCβ-lactamase were the Frame-shift mutations that could create the change of large region of amino acid.However,other mechanisms for the derepressed high-productive AmpCβ-lactamase were not excluded in the study.
Download(CAJ format) Download(PDF format)
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
©CNKI All Rights Reserved