Cloning and Characterization of Pseudomonas putida genes Encoding the Phosphate-Specific Transport System

摘要

The pstSCAB genes of Pseudomonas putida PRS2000, encoding the phosphate (P_1)-specific transport (Pst) system, were cloned. The pstS gene of Pseudomonas aeruginosa PAOI, of which the pstCAB genes had been cloned previously, was also cloned (Nikata, T. et al., Mol. Gen. Genet., 250, 692-698, 1996). The predicted translation products of the P. putida pstSCAB genes showed 83, 75, 78 and 88% amino acid identity with their P. aeruginosa counterparts. two well-conserved Pho box sequences were found in the region upstream of the pstS gene (15/18 base identity with the consensus Pho box sequence) and in the intercistronic region between the pstS and pstC genes (11/18 base identity) of P. putida PRS2000. To investigate the functions of PstSCAB, the pstSC genes were inactivated by inserting a kanamycin resistance gene cassette into the chromosome of P. putida PRS2000. The resultant mutant, designated PNI1, failed to take up ~(32)p_i even under conditions of P_i limitation. Strain PNT1 was also constitutive for alkaline phosphatase synthesis, as well as chemotaxis toward P_i, indicating that the Pst system is involved in the negative regulation of the pho regulon in P. putida. although overexpression of the pstSCAB genes in P. putida PRS2000 resulted in decreased cell growth, this recombinant strain could remove P_i at a rate similar to that seen with the control strain.