Isolation and characterization of rcsB mutations that affect colanic acid capsule synthesis in Escherichia coli K-12
Isolation and characterization of rcsB mutations that affect colanic acid capsule synthesis in Escherichia coli K-12
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DOI：
10.1128/jb.179.13.4328-4335.1997
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发表时间：
1997-07-01
影响因子：
3.2
通讯作者：
Stout, V
中科院分区：
文献类型：
--
作者：
Gupte, G;Woodward, C;Stout, V
在大肠杆菌中调节可可酸多糖胶囊的合成需要RCSC和RCSB蛋白，通过序列相似性，这两个蛋白似乎是在细菌中发现的双组分感受器-效应器调节家族的成员。我们已经在RCSB中分离出能够抑制RCSC‘’up‘’突变(即，导致cps转录增加)的突变，该突变通常会导致胶囊的结构性表达，此外，我们已经从突变体的特征中分离出RCSB中的结构性胶囊突变，通过类比Chey的三维结构，我们已经开始定义RCSB的不同结构域并赋予它们功能，一些结构性胶囊突变被定位在酸性口袋中，被认为在RCSB的磷酸化中发挥关键作用，就像在其他两组分系统中所看到的那样。RCSB的磷酸化位点上的天冬氨酸到谷氨酸的取代导致了结构性的被膜表达，最后，我们发现了几个RCSB突变体对RCSC的等位基因特异性(rcsC137特异性)，这表明RCSC和RCSB蛋白之间存在物理和功能上的相互作用。
Regulation of colanic acid polysaccharide capsule synthesis in Escherichia coli requires the proteins RcsC and RcsB, in addition to several other proteins, By sequence similarity, these two proteins appear to be members of the two-component sensor-effector regulatory family found in bacteria, The present study characterizes the functional domains of RcsB. We have isolated mutations in rcsB that are able to suppress an rcsC ''up'' mutation (i.e., leading to increase in cps transcription) that normally results in constitutive expression of the capsule, In addition, constitutive capsule mutations in rcsB have been isolated, From the characterization of the mutants and by analogy to the three-dimensional structure of CheY, we have begun to define different domains of RcsB and to assign functions to them, A few of the constitutive capsule mutations were localized in an acidic pocket that has been proposed to play a crucial role in phosphorylation of RcsB, As seen in other two-component systems, an aspartate-to-glutamate substitution at the presumed site of phosphorylation of RcsB resulted in constitutive capsule expression, Lastly, several of our rcsB mutants were found to he allele specific (rcsC137 specific) for rcsC, suggesting a physical as well as functional interaction between RcsC and RcsB proteins.