Transcription of ppk from Acinetobacter sp. Strain ADP1, encoding a putative polyphosphate kinase, is induced by phosphate starvation

Polyphosphate kinase (Ppk) catalyzes the formation of polyphosphate from ATP, We cloned the ppk gene (2,073 bp) from Acinetobacter sp, strain ADP1; this gene encodes a putative polypeptide of 78.6 kDa with extensive homology to polyphosphate kinase from Escherichia coli and other bacteria, Chromosomal disruption of ppk by inserting a transcriptionally fused lacZ does not affect growth under conditions of phosphate limitation or excess, beta-Galactosidase activity expressed from the single-copy ppk::lacZ fusion is induced 5- to 15-fold by phosphate starvation, An increased amount of ppk transcript (2.2 kb) was detected when cells were grown at a limiting phosphate concentration, Primer extension analysis revealed a regulated promoter located upstream of a second, constitutive promoter. Potential similarities of this regulation with the effects of PhoB and PhoR of E. coli are discussed.