| Research Abstract |
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.
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