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 fr om ATP, We cloned the ppk gene (2,073 bp) from Acinetobacter sp, strai n ADP1; this gene encodes a putative polypeptide of 78.6 kDa with exte nsive homology to polyphosphate kinase from Escherichia coli and other bacteria, Chromosomal disruption of ppk by inserting a transcriptiona lly fused lacZ does not affect growth under conditions of phosphate li mitation or excess, beta-Galactosidase activity expressed from the sin gle-copy ppk::lacZ fusion is induced 5- to 15-fold by phosphate starva tion, An increased amount of ppk transcript (2.2 kb) was detected when cells were grown at a limiting phosphate concentration, Primer extens ion analysis revealed a regulated promoter located upstream of a secon d, constitutive promoter. Potential similarities of this regulation wi th the effects of PhoB and PhoR of E. coli are discussed.