Aeromonas hydrophila AmpH and CepH β-lactamases:: derepressed expression in mutants of Escherichia coli lacking creB
Aeromonas hydrophila AmpH and CepH β-lactamases:: derepressed expression in mutants of Escherichia coli lacking creB
复制标题
DOI：
10.1093/jac/46.5.695
复制
发表时间：
2000-11-01
影响因子：
5.2
通讯作者：
Bennett, PM
中科院分区：
文献类型：
--
作者：
Avison, MB;Niumsup, P;Bennett, PM
从嗜水气单胞菌临床分离株T429125中克隆了一类头孢菌素酶（CepH）和一类苯唑西林酶（AmpH）。这两个克隆的β-内酰胺酶基因在标准实验室大肠杆菌菌株中均以低水平表达，但当克隆到cre缺失的大肠杆菌中时。coli突变体中，它们以显著更高的水平表达。creB基因的特异性破坏导致β-内酰胺酶表达水平的类似增加，因此得出结论，CreB抑制cre（+）E中ampH和cepH的转录。大肠杆菌菌株。在Delta cre突变体中，cepH的表达是ampH的4倍，这是因为在含有cepH的克隆的T429125染色体片段上编码的另外的因子。该因子能够反式激活Delta cre突变体中共存的ampH的表达，使得两个基因的表达大致相等。对整个含cepH的片段进行了测序，但它不包含与任何已知的DNA结合蛋白类明显相关的基因。
The class 1 cephalosporinase (CepH) and class 2d oxacillinase (AmpH) from an Aeromonas hydrophila clinical isolate, strain T429125, have been cloned and sequenced, Both enzymes are typical of their equivalents in other species of Aeromonas. Both cloned beta -lactamase genes were expressed at a low level in a standard laboratory Escherichia coli strain, but when cloned into a cre deletion E. coli mutant, they were expressed at significantly higher levels. Specific disruption of the creB gene resulted in similar increased levels of beta -lactamase expression, so it was concluded that CreB represses the transcription of ampH and cepH in a cre(+) E. coli strain. The expression of cepH was four times that of ampH in the Delta cre mutant because of an additional factor encoded on the cloned T429125 chromosomal fragment containing cepH, This factor was able to trans-activate expression of co-resident ampH in the Delta cre mutant such that expression of the two genes was approximately equal. The entire cepH-containing fragment was sequenced, but it contained no genes that were obviously related to any known class of DNA-binding protein.