Specific mutations of ampD gene leading to the emergence of derepressed high-production of AmpC β-lactamase
- VernacularTitle:阴沟肠杆菌染色质ampD基因定点突变致AmpCβ-内酰胺酶由非持续高产型转变为持续高产型
- Author:
Wan TU
;
Hu ZHAO
- Publication Type:Journal Article
- Keywords:
beta lactamases;
enterobacter cloacae;
Genes;
Mutation
- From:
International Journal of Laboratory Medicine
2010;31(1):4-7,10
- CountryChina
- Language:Chinese
-
Abstract:
Objective To reveal the influence factor of ampD specific mutation on the transformation of AmpC β-lactamase from non-high-productive type to derepressed the high-productive type in Enterobacter cloacae. Methods The selected cbromatin-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 ehromatin-mediated derepressed high-productive type,8 strains had significant mutations and 7 strains of site-directed mutagenesis were established. Ecl MA(274 inser-ting A)、Ecl MC(327 missing C)and Ecl MF(27 inserting G)were changed from non-high-productive type to derepressed-high-pro-ductive 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 AmpC β-lactamase types. Conclusion The significant mutations that could lead to the transformation of AmpC β-lacta-mase were the Frame-shift mutations that could create the change of large region of amino acid. However, other mechanisms for the derepressed high-productive AmpC β-lactamase were not excluded in the study.
