POSITIVE AND NEGATIVE CONTROL OF OMPB TRANSCRIPTION IN ESCHERICHIA-COLI BY CYCLIC-AMP AND THE CYCLIC-AMP RECEPTOR PROTEIN
POSITIVE AND NEGATIVE CONTROL OF OMPB TRANSCRIPTION IN ESCHERICHIA-COLI BY CYCLIC-AMP AND THE CYCLIC-AMP RECEPTOR PROTEIN
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DOI：
10.1128/jb.174.3.664-670.1992
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发表时间：
1992-02-01
影响因子：
3.2
通讯作者：
FREUNDLICH, M
中科院分区：
文献类型：
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作者：
HUANG, L;TSUI, P;FREUNDLICH, M
OmpB操纵子编码OmpR和EnvZ，这两种蛋白是OmpF和OMPC孔蛋白在大肠杆菌中表达和渗透调节所必需的。我们在体外和体内的实验表明，环状AMP和环状AMP受体蛋白(CRP)直接调节ompB。当细胞生长在含有贫碳源或添加环状AMP的培养基中时，ompB-LacZ染色体融合株中ompB的表达增加了两到五倍。体内引物延伸分析表明，这种控制是复杂的，涉及到环状AMP-CRP对多个ompB启动子的正负作用。体外足迹显示，环状AMP-CRP结合在一个34个碱基上，中心位于-53和-75，与主要转录本的起始位置有关，这些转录本分别被该复合体抑制和激活。C反应蛋白结合位点的定点突变提供了证据，证明该位点是环状AMP在体内调节ompB表达所必需的。环状AMP-CRP对ompB操纵子的控制可能解释了观察到的这种复合体对OmpF和OMPC形成的调节(N.W.Scott和C.R.Harwood，FEMS Microbiol。让我们来吧。9：95-98,1980)。
The ompB operon encodes OmpR and EnvZ, two proteins that are necessary for the expression and osmoregulation of the OmpF and OmpC porins in Escherichia coli. We have used in vitro and in vivo experiments to show that cyclic AMP and the cyclic AMP receptor protein (CRP) directly regulate ompB. ompB expression in an ompB-lacZ chromosomal fusion strain was increased two- to fivefold when cells were grown in medium containing poor carbon sources or with added cyclic AMP. In vivo primer extension analysis indicated that this control is complex and involves both positive and negative effects by cyclic AMP-CRP on multiple ompB promoters. In vitro footprinting showed that cyclic AMP-CRP binds to a 34-bp site centered at -53 and at -75 in relation to the start sites of the major transcripts that are inhibited and activated, respectively, by this complex. Site-directed mutagenesis of the crp binding site provided evidence that this site is necessary for the in vivo regulation of ompB expression by cyclic AMP. Control of the ompB operon by cyclic AMP-CRP may account for the observed regulation of the formation of OmpF and OmpC by this complex (N. W. Scott and C. R. Harwood, FEMS Microbiol. Lett. 9:95-98, 1980).