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PMID:10348860

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Citation

Vincent, C, Doublet, P, Grangeasse, C, Vaganay, E, Cozzone, AJ and Duclos, B (1999) Cells of Escherichia coli contain a protein-tyrosine kinase, Wzc, and a phosphotyrosine-protein phosphatase, Wzb. J. Bacteriol. 181:3472-7

Abstract

Two proteins of Escherichia coli, termed Wzc and Wzb, were analyzed for their capacity to participate in the reversible phosphorylation of proteins on tyrosine. First, Wzc was overproduced from its specific gene and purified to homogeneity by affinity chromatography. Upon incubation in the presence of radioactive ATP, it was found to effectively autophosphorylate. Two-dimensional analysis of its phosphoamino acid content revealed that it was modified exclusively at tyrosine. Second, Wzb was also overproduced from the corresponding gene and purified to homogeneity by affinity chromatography. It was shown to contain a phosphatase activity capable of cleaving the synthetic substrate p-nitrophenyl phosphate into p-nitrophenol and free phosphate. In addition, it was assayed on individual phosphorylated amino acids and appeared to dephosphorylate specifically phosphotyrosine, with no effect on phosphoserine or phosphothreonine. Such specificity for phosphotyrosine was confirmed by the observation that Wzb was able to dephosphorylate previously autophosphorylated Wzc. Together, these data demonstrate, for the first time, that E. coli cells contain both a protein-tyrosine kinase and a phosphotyrosine-protein phosphatase. They also provide evidence that this phosphatase can utilize the kinase as an endogenous substrate, which suggests the occurrence of a regulatory mechanism connected with reversible protein phosphorylation on tyrosine. From comparative analysis of amino acid sequences, Wzc was found to be similar to a number of proteins present in other bacterial species which are all involved in the synthesis or export of exopolysaccharides. Since these polymers are considered important virulence factors, we suggest that reversible protein phosphorylation on tyrosine may be part of the cascade of reactions that determine the pathogenicity of bacteria.

Links

PubMed PMC93815

Keywords

Adenosine Triphosphate/metabolism; Amino Acid Sequence; Base Sequence; Escherichia coli/enzymology; Molecular Sequence Data; Nitrophenols/metabolism; Organophosphorus Compounds/metabolism; Phosphorylation; Phosphotyrosine/metabolism; Protein Tyrosine Phosphatases/chemistry; Protein Tyrosine Phosphatases/genetics; Protein Tyrosine Phosphatases/isolation & purification; Protein Tyrosine Phosphatases/metabolism; Protein-Tyrosine Kinases/chemistry; Protein-Tyrosine Kinases/genetics; Protein-Tyrosine Kinases/isolation & purification; Protein-Tyrosine Kinases/metabolism; Recombinant Fusion Proteins/biosynthesis; Recombinant Fusion Proteins/isolation & purification; Recombinant Fusion Proteins/metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Substrate Specificity

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ECOLI:WZC

enables

GO:0004713: protein tyrosine kinase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:WZC

involved_in

GO:0038083: peptidyl-tyrosine autophosphorylation

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ECOLI:WZB

enables

GO:0004725: protein tyrosine phosphatase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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