[Chimeric SHA-D domain ("SH3-Bergerac"): 3D-structure and dynamics studies in solution].

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Dynamics

Context:

• The SH3 domain is a crucial protein module involved in diverse cellular signaling pathways.
• Spectrin SH3 domains, like those in the "SH3-Bergerac" family, play roles in cytoskeletal organization.
• Understanding modifications to these domains is key to deciphering protein function and interactions.

Purpose:

• To investigate the structural and dynamic consequences of substituting the N47-D48 beta-turn in a spectrin SH3 domain with the KATANDKTYE sequence, creating the SHA-D variant.
• To characterize the solution structure and dynamics of the SHA-D protein using high-resolution Nuclear Magnetic Resonance (NMR) spectroscopy.
• To compare the structural and dynamic properties of SHA-D with its wild-type counterpart (WT-SH3) and other members of the "SH3-Bergerac" family.

Summary:

• The SHA-D protein, a chimeric variant of a spectrin SH3 domain, was engineered by replacing the native beta-turn (N47-D48) with a KATANDKTYE amino acid sequence.
• High-resolution NMR studies demonstrated that while the overall 3D topology of SHA-D remains largely conserved compared to WT-SH3 and the "SH3-Bergerac" family, significant dynamic differences emerge.
• Specifically, a G52D substitution within SHA-D induces destabilization at the insertion site, promoting conformational exchange and leading to increased lability throughout the entire molecule.

Impact:

• The findings highlight how localized sequence modifications can subtly alter protein dynamics without drastic topological changes.
• This research provides insights into the relationship between protein sequence, structure, and dynamics, relevant for protein engineering and drug design.
• The increased lability observed in SHA-D suggests potential implications for its binding interactions and functional roles in cellular processes.