Phosphate Regulation of Gene Expression in Vibrio Parahaemolyticus

The synthesis of a major outer membrane protein, OmpP, in Vibrio parahaemolyticus was induced by growth in media deficient in phosphate. The gene, ompP, encoding this protein was cloned. Synthesis of OmpP in Escherichia coli was regulated by the availability of phosphate, and this control required the function of pho regulatory genes of E. coli. Analysis of gene fusion strains constructed by mutagenesis with transposon mini-Mulux revealed that ompP was transcriptionally regulated in V. parahaemolyticus. Impaired growth of a strain with an ompP defect was observed in media which contained large linear polyphosphates as the phosphate source. This and other evidence suggested that OmpP functions as a porin channel for the entry of phosphate into the cell. A number of other proteins or activities were induced by phosphate limitation including hemolysin, phospholipase C, and phosphatase activities. A regulatory locus controlling expression of phosphate-regulated genes was identified and cloned. This regulatory locus cloned from V. parahaemolyticus was shown to complement E. coli strains with defects in pho regulatory genes.