THE LEUCINE-RESPONSIVE REGULATORY PROTEIN OF ESCHERICHIA-COLI NEGATIVELY REGULATES TRANSCRIPTION OF OMPC AND MICF AND POSITIVELY REGULATES TRANSLATION OF OMPF
THE LEUCINE-RESPONSIVE REGULATORY PROTEIN OF ESCHERICHIA-COLI NEGATIVELY REGULATES TRANSCRIPTION OF OMPC AND MICF AND POSITIVELY REGULATES TRANSLATION OF OMPF
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DOI：
10.1128/jb.177.1.103-113.1995
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发表时间：
1995-01-01
影响因子：
3.2
通讯作者：
MATTHEWS, RG
中科院分区：
文献类型：
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作者：
FERRARIO, M;ERNSTING, BR;MATTHEWS, RG
大肠杆菌K-12菌株的两种主要孔蛋白OmpC和OmpF相对于彼此反向调节。已显示OmpC和OmpP的表达受亮氨酸响应调节蛋白（Lrp）的影响：来自具有和不具有功能性Lrp蛋白的菌株的蛋白质的二维凝胶电泳显示OmpC表达在Lrp菌株中增加，而OmpF表达减少。与这些发现一致，我们现在提出证据表明lacZ（+）与ompC和micF的转录（操纵子）融合受到Lrp的负调控。Lrp特异性结合micF和ompC之间的基因间区域，如迁移率变动测定和DNA酶I足迹所示。与lrp背景相比，在lrp（+）背景中ompF-lacZ（+）基因（翻译）融合体的表达增加了3.7倍，但ompF-lacZ（+）操纵子融合体的表达没有增加。在葡萄糖基本培养基上生长期间外膜孔蛋白的体内表达的研究表明，lrp（+）菌株中的OmpF/OmpC比率高于同基因lrp菌株。在含有micF缺失的菌株中未观察到Lrp的作用。我们的研究表明，Lrp对OmpF表达的积极影响源于Lrp对micF表达的负面影响，micF是一种抑制OmpF翻译的反义RNA。
The two major porins of Escherichia coli K-12 strains, OmpC and OmpF, are inversely regulated with respect to one another. The expression of OmpC and OmpP has been shown to be influenced by the leucine-responsive regulatory protein (Lrp): two dimensional gel electrophoresis of proteins from strains with and strains without a functional Lrp protein revealed that OmpC expression is increased in an lrp strain, while OmpF expression is decreased. In agreement,vith these findings, we now present evidence that transcriptional (operon) fusions of lacZ(+) to ompC and micF are negatively regulated by Lrp. Lrp binds specifically to the intergenic region between micF and ompC, as indicated by mobility shift assays and by DNase I footprinting. The expression of an ompF-lacZ(+) gene (translational) fusion is increased 3.7-fold in an lrp(+) background compared with an lrp background, but expression of an ompF-lacZ(+) operon fusion is not. Studies of in vivo expression of the outer membrane porins during growth on glucose minimal medium showed that the OmpF/OmpC ratio is higher in lrp(+) strains than it is in isogenic lrp strains. The effect of Lrp was not seen in a strain containing a deletion of micF. Our studies suggest that the positive effect of Lrp on OmpF expression stems from a negative effect of Lrp on the expression of micF, an antisense RNA that inhibits ompF translation.