Distal Regions Regulate Dihydrofolate Reductase-Ligand Interactions.

Protein motions play a fundamental role in enzyme catalysis and ligand binding. The relationship between protein motion and function has been extensively investigated in the model enzyme dihydrofolate reductase (DHFR). DHFR is an essential enzyme that catalyzes the reduction of dihydrofolate to tetrahydrofolate. Numerous experimental and computational methods have been used to probe the motions of DHFR through the catalytic cycle and to investigate the effect of distal mutations on DHFR motions and ligand binding. These experimental investigations have pushed forward the study of protein motions and their role in protein-ligand interactions. The introduction of mutations distal to the active site has been shown to have profound effects on ligand binding, hydride transfer rates and catalytic efficacy and these changes are captured by enzyme kinetics measurements. Distal mutations have been shown to exert their effects through a network of correlated amino acids and these effects have been investigated by NMR, protein dynamics, and analysis of coupled amino acids. The experimental methods and the findings that are reviewed here have broad implications for our understanding of enzyme mechanisms, ligand binding and for the future design and discovery of enzyme inhibitors.