Single Ion Pair Is Essential for Stabilizing SHP2's Open Conformation.

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Src-homology-2-domain-containing PTP-2 (SHP2) is a critical signaling enzyme implicated in human diseases.
• SHP2 activity is regulated by a balance between its inactive (closed) and active (open) conformations.
• Understanding SHP2's open state stabilization is vital for therapeutic strategies.

Purpose of the Study:

• To identify specific amino acid interactions stabilizing the active (open) conformation of SHP2.
• To investigate the biochemical basis of SHP2 open-state stabilization through mutagenesis.

Main Methods:

• Systematic mutagenesis of residues at interdomain interfaces of SHP2's open conformation.
• Evaluation of open/closed conformational equilibria for wild-type and mutant SHP2 proteins.

Main Results:

• Several amino acid interactions were found to stabilize the SHP2 open state.
• A critical ion pair between Glutamate 249 (PTP domain) and Arginine 111 (interdomain loop) was identified.
• Disruption of the R111/E249 ion pair significantly favors the closed (inhibited) state, creating 'hyperinhibited' SHP2 mutants.

Conclusions:

• The R111/E249 ion pair is a key determinant for stabilizing SHP2's active conformation.
• The identified 'hyperinhibited' SHP2 mutants offer novel tools for studying SHP2 signaling.
• These findings advance understanding of SHP2 regulation and its role in disease suppression.