PMID:12562757

Citation	Rajagopal, L, Clancy, A and Rubens, CE (2003) A eukaryotic type serine/threonine kinase and phosphatase in Streptococcus agalactiae reversibly phosphorylate an inorganic pyrophosphatase and affect growth, cell segregation, and virulence. J. Biol. Chem. 278:14429-41
Abstract	Protein phosphorylation is essential for the regulation of cell growth, division, and differentiation in both prokaryotes and eukaryotes. Signal transduction in prokaryotes was previously thought to occur primarily by histidine kinases, involved in two-component signaling pathways. Lately, bacterial homologues of eukaryotic-type serine/threonine kinases and phosphatases have been found to be necessary for cellular functions such as growth, differentiation, pathogenicity, and secondary metabolism. The Gram-positive bacteria Streptococcus agalactiae (group B streptococci, GBS) is an important human pathogen. We have identified and characterized a eukaryotic-type serine/threonine protein kinase (Stk1) and its cognate phosphatase (Stp1) in GBS. Biochemical assays revealed that Stk1 has kinase activity and localizes to the membrane and that Stp1 is a soluble protein with manganese-dependent phosphatase activity on Stk1. Mutations in these genes exhibited pleiotropic effects on growth, virulence, and cell segregation of GBS. Complementation of these mutations restored the wild type phenotype linking these genes to the regulation of various cellular processes in GBS. In vitro phosphorylation of cell extracts from wild type and mutant strains revealed that Stk1 is essential for phosphorylation of six GBS proteins. We have identified the predominant endogenous substrate of both Stk1 and Stp1 as a manganese-dependent inorganic pyrophosphatase (PpaC) by liquid chromatography/tandem mass spectrometry. These results suggest that these eukaryotic-type enzymes regulate pyrophosphatase activity and other cellular functions of S. agalactiae.
Links	PubMed Online version:10.1074/jbc.M212747200
Keywords	Alkaline Phosphatase/metabolism; Alleles; Amino Acid Sequence; Animals; Chromatography, Liquid; Cyclin-Dependent Kinases; DNA/metabolism; Electrophoresis, Gel, Two-Dimensional; Female; Genetic Complementation Test; Glutathione Transferase/metabolism; Inorganic Pyrophosphatase; Manganese/metabolism; Mass Spectrometry; Microscopy, Electron; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Open Reading Frames; Phenotype; Phosphorylation; Protein-Serine-Threonine Kinases/chemistry; Protein-Serine-Threonine Kinases/metabolism; Pyrophosphatases/metabolism; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins/metabolism; Reverse Transcriptase Polymerase Chain Reaction; Sequence Homology, Amino Acid; Streptococcus agalactiae/enzymology; Time Factors; Transcription, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRAG:Q8VQA0		GO:0004674: protein serine/threonine kinase activity	ECO:0000314:		F		Figure 2 shows that Stk1 phosphorylates at serine and threonine residues	complete CACAO 5342
STRAG:Q8VQA1		GO:0016791: phosphatase activity	ECO:0000314:		F		Figure 3 shows Stp1 hydrolyzing pNP-phosphate into pNP	complete CACAO 5343

References

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