The Polyphosphate Kinase Gene of Pseudomonas aeruginosa

We have cloned and sequenced a gene encoding polyphosphate kinase (PPK) from Pseudomonas aeruginosa PAO1. The gene immediately follows the hemB gene encoding porphobilinogen synthase responsible for heme synthesis. The predicted amino acid sequence of P. aeruginosa PPK is similar to those of PPKs previously characterized except that it possesses an extra stretch of 46 amino acids at its N-terminus, which has significant similarity to the Ras-related protein ARA5 of Arabidopsis thaliana. When P. aeruginosa PPK was overproduced in Escherichia coli, ATP-dependent polyphosphate-synthesizing activity was drastically enhanced, confirming that the protein is a PPK.