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Analyzing the catalytic mechanism of protein tyrosine phosphatase PtpB from Staphylococcus aureus through

Somnath Mukherjee1, Riddhiman Dhar, Amit Kumar Das

  • 1Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India.

International Journal of Biological Macromolecules
|September 15, 2009
PubMed

Insights

Staphylococcus aureus Protein tyrosine phosphatase B (PtpB) is crucial for pathogenicity. Key active site mutations significantly reduced PtpB

Area of Science:

  • Biochemistry
  • Microbiology
  • Enzymology

Background:

  • Protein tyrosine phosphatase B (PtpB) from Staphylococcus aureus (MRSA 252) is a low molecular weight protein tyrosine phosphatase (LMWPTPase).
  • PtpB plays a significant role in the pathogenicity of Staphylococcus aureus.
  • Understanding the catalytic mechanism of PtpB is essential for developing targeted inhibitors.

Purpose of the Study:

  • To investigate the role of active site residues (Cys8, Arg14, Ser15, Asp120) in the catalytic mechanism of PtpB.
  • To characterize the kinetic properties of wild-type and mutant PtpB enzymes.
  • To explore the inhibition kinetics of wild-type PtpB.

Main Methods:

  • In silico modeling of PtpB.
  • Site-directed mutagenesis of active site residues.
  • Kinetic characterization of wild-type and mutant enzymes.
  • Inhibition kinetics assays using maleimide and maleimidobutyric acid.

Main Results:

  • Mutations in active site residues (C8S, R14A, S15T/A, D120A/E/N) significantly altered the local environment of PtpB.
  • Catalytic activity of all tested PtpB mutants was substantially decreased compared to the wild-type enzyme.
  • Kinetic characterization elucidated the reaction mechanism of this LMWPTPase.

Conclusions:

  • Active site residues Cys8, Arg14, Ser15, and Asp120 are critical for the catalytic function of PtpB.
  • The identified mutations demonstrate the importance of these residues in maintaining PtpB's enzymatic activity.
  • Further studies on PtpB inhibition are warranted.

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