Abstract
A gene, ppx, that encodes a novel exopolyphosphatase of 513 amino acids (58,133 Da) was found downstream of the gene for polyphosphate kinase, ppk. Transcription of the ppx gene depends on the ppk promoters, indicating a polyphosphate (polyP) operon of ppk and ppx. Exopolyphosphatase, purified to homogeneity from overproducing cells, is judged to be a dimer of 58-kDa subunits. Orthophosphate is released processively from the ends of polyP approximately 500 residues long, but chains of approximately 15 residues compete poorly with polyP as substrate; ATP is not a substrate. Mg2+ (1 mM) and a high concentration of K+ (175 mM) support optimal activity.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acid Anhydride Hydrolases*
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Amino Acid Sequence
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Base Sequence
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Chromatography, Ion Exchange
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DNA, Bacterial / genetics
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DNA, Bacterial / isolation & purification
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Escherichia coli / enzymology*
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Escherichia coli / genetics*
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Genes, Bacterial*
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Kinetics
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Macromolecular Substances
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Magnesium Chloride / pharmacology
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Molecular Sequence Data
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Operon*
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Phosphoric Monoester Hydrolases / genetics*
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Phosphoric Monoester Hydrolases / isolation & purification
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Phosphoric Monoester Hydrolases / metabolism*
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Plasmids
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Polyphosphates / metabolism
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Restriction Mapping
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Substrate Specificity
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Thermodynamics
Substances
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DNA, Bacterial
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Macromolecular Substances
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Polyphosphates
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Recombinant Proteins
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Magnesium Chloride
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Phosphoric Monoester Hydrolases
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Acid Anhydride Hydrolases
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exopolyphosphatase