Degradation of Inorganic Polyphosphate in Mutants ofAerobacter aerogenes

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Abstract
Harold, F. M. (National Jewish Hospital, Denver, Colo.),and Ruth L. Harold. Degradation of inorganic polyphosphate in mutants ofAerobacter aerogenes. J. Bacteriol.89:1262–1270. 1965.—Extracts ofAerobacter aerogenescontained two enzymes capable of degrading polyphosphate, polyphosphatase and polyphosphate kinase. By use of a suicide technique, a mutant (Pn-4) blocked in polyphosphate degradation was isolated; this mutant was found to lack polyphosphatase. The results indicate that polyphosphatase mediates the main pathway of polyphosphate degradation, and, therefore, that polyphosphate does not serve as a microbial phosphagen. A second mutant (Pn-3) exhibited transient accumulation of polyphosphate when cells were transferred to fresh growth medium. This strain was constitutive for elevated levels of polyphosphate kinase, polyphosphatase, and alkaline phosphatase; the transient accumulation of polyphosphate may be due to the shifting ratios of the biosynthetic and degradative enzymes during growth. These mutants were employed in studies on the competitive relationship between polyphosphate and nucleic acids. It was concluded that nucleic acid synthesis inhibits polyphosphate synthesis and also stimulates polyphosphate degradation.