Roychoudhury S, Sakai K, Schlictman D, Chakrabarty A M
Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago 60612.
Gene. 1992 Mar 1;112(1):45-51. doi: 10.1016/0378-1119(92)90301-5.
Synthesis of alginate by Pseudomonas aeruginosa correlates with its pathogenicity in the lungs of patients suffering from cystic fibrosis (CF). Alginate synthesis-encoding genes (alg) in P. aeruginosa are normally silent, but are specifically triggered in the CF lung environment. The promoter for the algD gene, located at the upstream end of the alg cluster, is activated by environmental factors such as high osmolarity, nutrient limitation and dehydration. Several regulatory proteins are known to control transcription from the algD promoter. Among these proteins is AlgR1 which is homologous to the phosphorylation-dependent response regulators of the two-component signal transduction system. In this paper, we report that AlgR2, an 18-kDa protein which in cooperation with AlgR1 regulates the algD promoter, undergoes phosphorylation in the presence of ATP. The phosphate group acquired by AlgR2 is then transferred to AlgR1. In addition, we show that AlgR1 can be phosphorylated by an AlgR2-analog in Escherichia coli. AlgR1 is isolated in a phosphorylatable 80-kDa complex in association with AlgR2 in P. aeruginosa and the AlgR2-analog in E. coli.
铜绿假单胞菌合成藻酸盐与其在囊性纤维化（CF）患者肺部的致病性相关。铜绿假单胞菌中编码藻酸盐合成的基因（alg）通常处于沉默状态，但在CF肺部环境中会被特异性激活。位于alg基因簇上游末端的algD基因启动子会被高渗透压、营养限制和脱水等环境因素激活。已知有几种调节蛋白控制algD启动子的转录。其中一种蛋白是AlgR1，它与双组分信号转导系统中依赖磷酸化的应答调节因子同源。在本文中，我们报道了一种18 kDa的蛋白AlgR2，它与AlgR1协同调节algD启动子，在ATP存在的情况下会发生磷酸化。AlgR2获得的磷酸基团随后转移到AlgR1上。此外，我们还表明AlgR1可以被大肠杆菌中的一种AlgR2类似物磷酸化。在铜绿假单胞菌中，AlgR1与AlgR2结合形成一个可磷酸化的80 kDa复合物，在大肠杆菌中则与AlgR2类似物结合。
