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Microbiology. 2002 Jun;148(Pt 6):1805-11.

HPr kinase/phosphatase of Bacillus subtilis: expression of the gene and effects of mutations on enzyme activity, growth and carbon catabolite repression.

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Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058 Erlangen, Germany.


HPr kinase/phosphatase (HPrK/P) is the key protein in regulation of carbon metabolism in Bacillus subtilis and many other Gram-positive bacteria. Whether this enzyme acts as a kinase or phosphatase is determined by the nutrient status of the cell. Mutational analysis of residues in a Walker A box nucleotide-binding motif revealed that it is not only important for kinase but is also involved in phosphatase activity. In addition, a signature sequence specifically conserved among HPrK/P orthologues is required for phosphatase activity and may be involved in interaction with HPr/HPr-(Ser46)-P. Carbon catabolite repression was abolished in a B. subtilis strain expressing a mutant form of HPrK/P deficient in kinase and phosphatase activities. The growth characteristics of this strain were similar to those of the wild-type. In contrast, B. subtilis strains expressing HPrK/P with partial kinase and no phosphatase activities showed growth impairment but exhibited catabolite repression.

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