Signal transduction map and direct control of cellular actvivities of bacteria

当细胞缺乏P_i时，铜绿假单胞菌被P_<i'>吸引。对P_i的士的调控不依赖PhoB和PhoR，而需要PhoU。P.aeruginosa pst基因产物是P_i特异性运输所必需的，也参与了P_i趋近性的负调控。然而，对于P_i出租车是否存在正调节器是未知的。目前对P_i化学感受器一无所知。在铜绿假单胞菌的一个大基因簇中，已鉴定出cheY、cheZ、cheA、cheB和cheJ 5个趋化基因。预测的前四个基因的蛋白质与已知的大肠杆菌Che蛋白质相似。然而，CheJ蛋白与任何已知的蛋白序列都没有明显的同源性。这种推测的蛋白可能在铜绿假单胞菌的趋化信号转导途径中发挥意想不到的作用。三个可能的趋化传感器基因pctA，pctB和pctC也被克隆和测序。基因产物与肠道MCPs具有结构同源性。铜绿假单胞菌的趋化性研究将在以下方面展开：(1)P_i趋化受体的鉴定；（ii）寻找其他趋化基因；（三）克隆尚待鉴定的趋化传感器基因。

P.aeruginosa is attracted toward P_<i'> when the cells are starved for P_i. Regulation of P_i taxis is not dependent on PhoB and PhoR but requires PhoU.The P.aeruginosa pst gene products, which are required for P_i-specific transport, are also involved in the negative regulation of P_i taxis. However, it is unknown whether a positive regulator exists for P_i taxis. Nothing is known about the P_i chemoreceptor at this time. Five chemotaxis genes, including the cheY,cheZ,cheA,cheB and cheJ,have been identified in a large gene cluster of P.aeruginosa. The predicted proteins of the first four genes resemble known E.coli Che proteins. However, the CheJ protein has no significant homology with any known protein sequences. This putative protein may play an unexpected role in the chemotactic signal-transduction pathway in P.aeruginosa. Three possible chemotactic transducer genes, pctA,pctB and pctC,have also been cloned and sequenced. The gene products have structural homology with the enteric MCPs. Our future work on the chemotaxis of P.aeruginosa will be directed at (i) identifying P_i chemoreceptor ; (ii) seeking out additional chemotaxis genes ; and (iii) cloning chemotactic transducer genes that remain to be identified.