Stout V, Gottesman S
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892.
J Bacteriol. 1990 Feb;172(2):659-69. doi: 10.1128/jb.172.2.659-669.1990.
Colanic acid capsule synthesis in Escherichia coli K-12 is regulated by RcsB and RcsC. The amino acid sequences of these two proteins, deduced from the nucleotide sequence reported here, demonstrate their homology to environmentally responsive two-component regulators that have been reported in both gram-positive and gram-negative bacteria. In our model, RcsC acts as the sensor and RcsB acts as the receiver or effector to stimulate capsule synthesis from cps genes. In addition, RcsC shows limited homology to the other effectors in its C terminus. Fusions of rcsC to phoA that resulted in PhoA+ strains demonstrated that RcsC is a transmembrane protein with a periplasmic N-terminal domain and cytoplasmic C-terminal domain. Additional control of this regulatory network is provided by the dependence on the alternate sigma factor, RpoN, for the synthesis of RcsB. The rcsB and rcsC genes, which are oriented convergently with their stop codons 196 base pairs apart, are separated by a long direct repeat including two repetitive extragenic palindromic sequences.
大肠杆菌K-12中柯拉酸胶囊的合成受RcsB和RcsC调控。根据本文报道的核苷酸序列推导的这两种蛋白质的氨基酸序列，显示出它们与革兰氏阳性菌和革兰氏阴性菌中报道的环境响应双组分调节因子具有同源性。在我们的模型中，RcsC作为传感器，RcsB作为接收器或效应器，刺激来自cps基因的胶囊合成。此外，RcsC在其C末端与其他效应器显示出有限的同源性。rcsC与phoA的融合产生了PhoA+菌株，表明RcsC是一种跨膜蛋白，具有周质N末端结构域和细胞质C末端结构域。RcsB的合成对替代西格玛因子RpoN的依赖性为该调节网络提供了额外的控制。rcsB和rcsC基因以相反方向排列，其终止密码子相距196个碱基对，它们被一个长的直接重复序列隔开，该重复序列包括两个重复的基因外回文序列。
