NSP-Cas protein structures reveal a promiscuous interaction module in cell signaling

Area of Science:

• Molecular Biology
• Cell Signaling
• Structural Biology

Background:

• Novel SH2-containing proteins (NSPs) and Crk-associated substrate (Cas) proteins are key regulators of cell migration and invasion.
• These protein families form multidomain signaling platforms via their C-terminal domains.
• The precise mechanism of NSP-Cas interaction has remained unclear.

Purpose of the Study:

• To elucidate the structural mechanism underlying the interaction between NSP and Cas protein families.
• To determine the crystal structures of the C-terminal domain of BCAR3 (an NSP) and the NSP3-p130Cas complex.

Main Methods:

• X-ray crystallography was employed to determine the structures.
• Analysis of the structural conformation of BCAR3 and the NSP3-p130Cas complex.

Main Results:

• BCAR3 exhibits a Cdc25-homology fold in a 'closed' conformation, lacking enzymatic activity.
• The NSP3-p130Cas complex structure reveals that this closed conformation facilitates interaction with the focal adhesion-targeting domain of Cas proteins.
• This structural insight demonstrates an enzyme-to-adaptor conversion in NSP proteins.

Conclusions:

• The study reveals an unprecedented mechanism for NSP-Cas protein interactions.
• This interaction, mediated by a closed conformation of NSPs, enables high-affinity, promiscuous binding.
• The findings provide a new mechanistic paradigm linking cellular signaling networks involved in cell migration.