REGULATION OF VIRULENCE-ASSOCIATED PLASMID GENES IN ENTEROINVASIVE ESCHERICHIA-COLI
REGULATION OF VIRULENCE-ASSOCIATED PLASMID GENES IN ENTEROINVASIVE ESCHERICHIA-COLI
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DOI：
10.1128/jb.174.23.7606-7612.1992
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发表时间：
1992-12-01
影响因子：
3.2
通讯作者：
UHLIN, BE
中科院分区：
文献类型：
--
作者：
DAGBERG, B;UHLIN, BE
转座子TnphoA被用于构建基因融合体和用于大肠杆菌肠侵袭性菌株中基因调控的研究。几种质粒编码的毒力基因（例如，这种肠侵袭性菌株的ipaB和virG操纵子）受到涉及操纵子特异性（VirB和VirF激活子）和全局调节子的协调的温度调节。核相关E.大肠杆菌蛋白H-NS被证明是一个负调节剂，通过使用H-NS基因缺失突变的研究和通过增加细胞中H-NS蛋白的水平来判断。H-NS基因剂量的增加导致ipa和virG操纵子的抑制增强，特别是在低（30 ℃）生长温度下。环AMP受体蛋白复合物是大肠杆菌中另一个全局性的转录调节因子。coli中，ipa和virG的表达调控并不需要。virG操纵子在缺乏H-NS蛋白的细胞中以不依赖于激活子的方式表达。我们认为VirF激活剂的作用是抵消H-NS的沉默效应。
The transposon TnphoA was used for construction of gene fusions and for studies of gene regulation in an enteroinvasive strain of Escherichia coli. Several plasmid-encoded virulence genes (e.g., the ipaB and virG operons) of such enteroinvasive strains are subject to coordinated thermoregulation involving both operon-specific (the VirB and VirF activators) and global regulators. The nucleoid-associated E. coli protein H-NS was shown to be a negative regulator as judged by studies using H-NS gene deletion mutations and by increasing the level of H-NS protein in the cells. An increased gene dosage of H-NS led to enhanced repression of the ipa and virG operons, particularly at low (30-degrees-C) growth temperature. The cyclic AMP receptor protein complex, which is another global transcriptional regulator in E. coli, was not required for the regulation of ipa and virG expression. The virG operon was expressed in an activator-independent manner in cells lacking H-NS protein. We suggest that the role of the VirF activator is to counteract the silencing effect of H-NS.