Apr 15, 2020

Substrate binding and turnover modulate the affinity landscape of dihydrofolate reductase to increase its catalytic efficiency

BioRxiv : the Preprint Server for Biology
N. S. Galenkamp, Giovanni Maglia


It is generally accepted that enzymes structures evolved to stabilize the transition-state of a catalyzed reaction. Here, observing single molecules with a multi-turnover resolution, we provide experimental evidence for a more sophisticated narrative. We found that the binding of the NADPH cofactor to DHFR induces a first allosteric change that increases the affinity of the enzyme for the substrate. Then the enthalpy generated by the chemical step provides a power stroke that switches the enzyme to the product-bound conformations and promotes the release of the oxidized cofactor NADP+. The subsequent binding of NADPH to the vacated site provides the free energy for the recovery stroke, which induces the allosteric release of the product and resets the initial configuration. Intriguingly, the cycle is not perfect. Occasionally, DHFR undergoes second-long catalytic pauses, most likely reflecting the occupancy of an off-path conformation induced by excess energy liberated by the chemical step. This catalytic remodeling of the affinity landscape of DHFR is likely to have evolved to improve the efficiency of the reaction to cope with the high concentration of NADP+ in E. coli. And might be a general feature for complex enzymatic rea...Continue Reading

  • References
  • Citations


  • We're still populating references for this paper, please check back later.
  • References
  • Citations


  • This paper may not have been cited yet.

Mentioned in this Paper

Trees (plant)
Phylogenetic Analysis
Mature T Cell Lineage Lymphoma of the Mouse Hematologic System
Unbiased Estimation
Dideoxy Chain Termination DNA Sequencing
Mucus (Mmhcc)

Related Feeds

BioRxiv & MedRxiv Preprints

BioRxiv and MedRxiv are the preprint servers for biology and health sciences respectively, operated by Cold Spring Harbor Laboratory. Here are the latest preprint articles (which are not peer-reviewed) from BioRxiv and MedRxiv.