Protein Kinase Structure and Dynamics: Role of the αC-β4 Loop.

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• The αC-β4 loop is a conserved secondary structure motif in protein kinases.
• Its role in maintaining the hydrophobic core architecture and its functional significance are underappreciated.
• The hydrophobic spine architecture of protein kinases was previously identified using Local Spatial Pattern (LSP) alignment.

Approach:

• A review of the αC-β4 loop motif and its connection to the kinase core's hydrophobic spine.
• Utilizing Local Spatial Pattern (LSP) alignment to analyze the F100A mutant, informed by NMR predictions.
• Investigating the structural dynamics of the apo C-subunit (lacking ATP) to understand allosteric regulation.

Key Points:

• LSP analysis of the F100A mutant revealed the critical importance of the αC-β4 loop and interface residues.
• NMR predictions suggested that mutations in this loop abolish synergistic binding of ATP and inhibitors.
• Analysis of the apo C-subunit showed altered side chain dynamics in K105, but not backbone dynamics in the αC-β4 loop.

Conclusions:

• The F100A mutation disrupts communication between the N- and C-lobes of the kinase.
• These findings align with NMR spectroscopy predictions regarding structural changes.
• The αC-β4 loop plays a vital role in allosteric regulation and kinase function.