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Streptococcus thermophilus Wzh functions as a phosphotyrosine phosphatase
Canadian Journal of Microbiology
  • A. D. Cefalo
  • Jeffery R. Broadbent, Utah State University
  • D. L. Welker
Document Type
Canadian Science Publishing
Publication Date
Amino acid residues that are important for metal binding and catalysis in Gram-positive phosphotyrosine phosphatases were identified in the Wzh protein of Streptococcus thermophilus MR-1C by using sequence comparisons. A His-tagged fusion Wzh protein was purified from Escherichia coli cultures and tested for phosphatase activity against synthetic phosphotyrosine and phosphoserine–threonine peptides. Purified Wzh released 2316.5 ± 138.7 pmol PO4·min−1·μg−1 from phosphotyrosine peptide-1 and 2345.7 ± 135.2 pmol PO4·min−1·μg−1 from phosphotyrosine peptide-2. The presence of the phosphotyrosine phosphatase inhibitor sodium vanadate decreased purified Wzh activity by 45%–50% at 1 mmol·L–1, 74%–84% at 5 mmol·L–1, and by at least 88% at 10 mmol·L–1. Purified Wzh had no detectable activity against the phosphoserine–threonine peptide. These results clearly establish that S. thermophilus MR-1C Wzh functions as a phosphotyrosine phosphatase that could function to remove phosphate groups from proteins involved in exopolysaccharide biosynthesis, including the protein tyrosine kinase Wze and priming glycosyltransferase.
Citation Information
Cefalo, A. D., J. R. Broadbent, and D. L. Welker. 2013. Streptococcus thermophilus Wzh functions as a phosphotyrosine phosphatase. Can. J. Microbiol. 59:391-398.