SIGNAL TRANSDUCTION IN THE PHOSPHATE REGULON OF ESCHERICHIA-COLI INVOLVES PHOSPHOTRANSFER BETWEEN PHOR AND PHOB PROTEINS
SIGNAL TRANSDUCTION IN THE PHOSPHATE REGULON OF ESCHERICHIA-COLI INVOLVES PHOSPHOTRANSFER BETWEEN PHOR AND PHOB PROTEINS
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DOI：
10.1016/0022-2836(89)90131-9
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发表时间：
1989-12-05
影响因子：
5.6
通讯作者：
NAKATA, A
中科院分区：
文献类型：
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作者：
MAKINO, K;SHINAGAWA, H;NAKATA, A
PHOB蛋白是缺磷诱导的大肠杆菌磷酸调节蛋白基因的转录激活子，如phA和pstS。当磷酸盐不足时，Phor蛋白激活Phob，当磷酸盐过多时，Phor蛋白使其失活。我们构建了一个含有突变的phor基因(PhoR1084)的质粒，该基因编码一个缺失完整蛋白氨基末端疏水区的phor蛋白(PhoR1084)。携带该质粒的细胞产生过量的PhoR1084，并在细胞裂解物的可溶部分中回收。我们纯化了Phor1084蛋白，结果表明，在ATP存在下，Phor1084蛋白被自动磷酸化，并且蛋白上的磷酸基团迅速转移到Phob上。Phob蛋白的磷酸化与从pstS启动子获得激活转录的能力同时发生。在这些发现的基础上，我们认为，磷酸化的Phob蛋白激活了来自磷酸调节子启动子的转录，并且Phor的作用是催化磷酸化的Phob的形成和分解，以响应介质中的磷浓度。
PhoB protein is the transcriptional activator for genes in the phosphate regulon of Escherichia coli, such as phoA and pstS, that are induced by phosphate deprivation. PhoR protein activates PhoB when phosphate is limiting and inactivates it when phosphate is in excess. We constructed a plasmid with a mutant phoR gene (phoR1084), which encoded a PhoR protein (PhoR1084) lacking the amino-terminal hydrophobic region of the intact protein. The cells carrying the plasmid overproduced PhoR1084, which was recovered in the soluble fraction of the cell lysate. We purified the Phor1084 protein and showed that it was autophosphorylated in the presence of ATP, and the phosphate group on the protein was rapidly transferred to PhoB. The phosphorylation of PhoB protein occurred concurrently with the acquisition of the ability to activate transcription from the pstS promoter. On the basis of these findings, we propose that phosphorylated PhoB protein activates transcription from the promoters of the phosphate regulon, and that the role of PhoR is to catalyze the formation and breakdown of phosphorylated PhoB in response to phosphate concentration in the medium.