The dynamic energy landscape of dihydrofolate reductase catalysis.
We used nuclear magnetic resonance relaxation dispersion to characterize higher energy conformational substates of Escherichia coli dihydrofolate reductase. Each intermediate in the catalytic cycle samples low-lying excited states whose conformations resemble the ground-state structures of preceding and following intermediates. Substrate and cofactor exchange occurs through these excited substates. The maximum hydride transfer and steady-state turnover rates are governed by the dynamics of transitions between ground and excited states of the intermediates. Thus, the modulation of the energy landscape by the bound ligands funnels the enzyme through its reaction cycle along a preferred kinetic path.
Boehr
David D
DD
Department of Molecular Biology and Skaggs Institute for Chemical Biology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
McElheny
Dan
D
Dyson
H Jane
HJ
Wright
Peter E
PE
D001665:Binding Sites; D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D009249:NADP / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism*; D013763:Tetrahydrofolates / Q000378:metabolism; D013816:Thermodynamics
D008024:Ligands; D013763:Tetrahydrofolates; C030371:5,6,7,8-tetrahydrofolic acid; D009249:NADP; D013762:Tetrahydrofolate Dehydrogenase