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Dephosphorylation of the phosphoprotein P II in Synechococcus PCC 7942: identification of an ATP and 2‐oxoglutarate‐regulated phosphatase activity
Author(s) -
Irmler Angelika,
Sanner Silvia,
Dierks Henning,
Forchhammer Karl
Publication year - 1997
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1997.5521918.x
Subject(s) - dephosphorylation , phosphatase , biology , phosphoserine , phosphorylation , biochemistry , kinase , microbiology and biotechnology , serine
The phosphorylation state of the putative signal transduction protein P II from the cyanobacterium Synechococcus sp. strain PCC 7942 depends on the cellular state of nitrogen and carbon assimilation. In this study, dephosphorylation of phosphorylated P II protein (P II ‐P) was investigated both in vivo and in vitro . The in vivo studies implied that P II ‐P dephosphorylation is regulated by inhibitory metabolites involved in the glutamine synthetase–glutamate synthase pathway of ammonium assimilation. An in vitro assay for P II ‐P dephosphorylation was established that revealed a Mg 2+ ‐dependent P II ‐P phosphatase activity. P II ‐P phosphatase and P II kinase activities could be separated biochemically. A partially purified P II ‐P phosphatase preparation also catalysed the dephosphorylation of phosphoserine/phosphothreonine residues on other proteins in a Mg 2+ ‐dependent manner. However, only dephosphorylation of P II ‐P was regulated by synergistic inhibition by ATP and 2‐oxoglutarate. As the same metabolites stimulate the P II kinase activity, it appears that the phosphorylation state of P II is determined by ATP and 2‐oxoglutarate‐dependent reciprocal reactivity of P II towards its phosphatase and kinase.