Macromolecular Crowding Induces a Binding Competent Transient Structure in Intrinsically Disordered Gab1

Area of Science:

• Biochemistry
• Protein Science
• Molecular Biology

Background:

• Intrinsically disordered proteins (IDPs) lack stable tertiary structures and are influenced by cellular environment and modifications.
• The C-terminal region of Gab1 (Gab1613-694) binds to SHP2, a process typically mediated by tyrosine phosphorylation.
• Cellular crowding and post-translational modifications can alter protein dynamics and function.

Purpose of the Study:

• To investigate how cellular crowding and tyrosine phosphorylation affect the structure and SHP2 binding of the Gab1 C-terminal region.
• To characterize induced structural motifs and their role in protein-protein interactions.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Circular Dichroism (CD) spectroscopy
• Isothermal Titration Calorimetry (ITC)
• Use of chemical and biological crowding agents

Main Results:

• Crowding conditions induced pre-structured motifs in two distinct regions of Gab1613-694.
• These induced structures were identical to the SHP2 binding sites.
• Tyrosine phosphorylation did not significantly alter Gab1's dynamics or intrinsically disordered nature.
• Crowding agents enhanced the binding capacity of Gab1 to SHP2, even without phosphorylation.

Conclusions:

• Cellular macromolecules can stabilize preformed binding states in intrinsically disordered proteins.
• Crowding can promote binding of Gab1 to SHP2 by inducing structure, independent of tyrosine phosphorylation.
• This suggests a mechanism by which cellular environment influences protein interactions and function.