Genetic and physiological studies of the CiaH-CiaR two-component signal-transducing system involved in cefotaxime resistance and competence of Streptococcus pneumoniae
Genetic and physiological studies of the CiaH-CiaR two-component signal-transducing system involved in cefotaxime resistance and competence of Streptococcus pneumoniae
复制标题
DOI：
10.1099/13500872-145-8-1859
复制
发表时间：
1999-08-01
期刊：
影响因子：
--
通讯作者：
Gasc, AM
中科院分区：
文献类型：
--
作者：
Giammarinaro, P;Sicard, M;Gasc, AM
肺炎链球菌ciaH基因突变导致头孢噻肟耐药和转化缺陷。CIAH编码一种可能的感受器蛋白，属于信号转导组氨酸蛋白激酶家族。这个基因与Ciar相邻，Ciar编码一种DNA结合蛋白，参与对组氨酸激酶感知的环境信号做出反应的基因的调节。作者已经确定了一种突变的特征，该突变导致头孢噻肟耐药性和转化缺陷的逆转。这是Ciar基因的T/A缺失，导致合成的截短蛋白质只包含125个氨基酸，而不是224个氨基酸。CiaH突变需要有功能的Clap蛋白才能表达。以Ciar-ciaH为探针的Northern印迹分析显示，野生型菌株中有一个mRNA，表明这两个基因构成一个操纵子。Northern杂交的比较表明，在只携带ciaH突变的菌株中，操纵子被结构性地激活。在野生型菌株中，当Ca~(2+)浓度很低时，激活发生，表明Ca~(2+)是环境信号。CiaH突变引起的多效性效应包括对抗生素和毒素的敏感性，形成原生质体的能力，以及对脱氧胆酸盐裂解的敏感性。在两个基因中都构建了零突变体，并确定了Ciar零突变体的特定特征。它能够在缺乏胆碱的介质中生长，并且在没有磷的能力介质(CH-马来酸)中发生能力发展，这表明CiaH-Ciar系统调节几个途径，包括磷脂酸的合成。
A mutation in the ciaH gene of Streptococcus pneumoniae induces cefotaxime resistance and transformation deficiency. ciaH encodes a putative sensor protein that belongs to the family of signal-transducing histidine kinases. This gene is adjacent to ciaR, which encodes a DNA-binding protein involved in the regulation of genes responding to environmental signals sensed by the histidine kinase. The authors have characterized a mutation that induces reversion of both cefotaxime resistance and transformation deficiency. It is a T/A deletion in the ciaR gene resulting in the synthesis of a truncated protein containing only 125 amino acids instead of 224. The ciaH mutation requires a functional Clap protein for expression. Northern blot analysis, using ciaR-ciaH as a probe, revealed one mRNA from the wild-type strain, indicating that the two genes constitute an operon. Comparisons of Northern blots show that the operon is constitutively activated in the strain carrying only the ciaH mutation. In the wild-type strain the activation occurs when the Ca2+ concentration is very low, demonstrating that Ca2+ is the environmental signal. The pleiotropic effects caused by the ciaH mutation include sensitivity to antibiotics and toxins, the ability to form protoplasts and the susceptibility to lysis with deoxycholate. Null-mutants were constructed in both genes and the particular features of the ciaR null mutant determined. It is able to grow in choline-deprived medium, and competence development occurs in a phosphate-deprived competence medium (CH-maleate), suggesting that the CiaH-CiaR system regulates several pathways, including teiochoic acid synthesis.