Distal Mutations Rewire Allosteric Networks to Control Substrate Specificity in PTP1B

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Protein Tyrosine Phosphatase 1B (PTP1B) is crucial for cellular signaling, with dysregulation linked to metabolic and oncologic diseases.
• Allosteric regulation of PTP1B by distal sites is not well understood, limiting therapeutic targeting.

Purpose of the Study:

• To investigate how mutations at four distal allosteric sites impact PTP1B's substrate specificity and enzymatic dynamics.
• To elucidate the molecular mechanisms underlying allosteric regulation in PTP1B.

Main Methods:

• Site-directed mutagenesis of PTP1B at Y153, I275, M282, and E297.
• Enzymatic kinetic analyses using phosphotyrosine peptides and p-nitrophenylphosphate.
• Solution Nuclear Magnetic Resonance (NMR) spectroscopy and microsecond molecular dynamics simulations.

Main Results:

• Allosteric mutations significantly altered PTP1B's catalytic efficiency and substrate preference.
• Mutations disrupted long-range communication networks, affecting helix coupling and active-site dynamics.
• The E297A mutation most profoundly impacted the acid loop and allosteric communication.

Conclusions:

• Distal mutations can reshape PTP1B's dynamic landscape, modulating substrate specificity.
• The acid loop and helix α7 are key hubs for allosteric communication in PTP1B.
• Understanding these dynamic networks offers a framework for controlling PTP1B activity therapeutically.