Mechanistic and Molecular Dynamics Studies Reveal that Increased Loop 3 Mobility Alters Substrate Capture in an NADH:Quinone Oxidoreductase.

ABSTRACT: Dynamic protein loops can act as molecular gates that stabilize enzyme-substrate complexes, yet the underlying motions are poorly defined. Here, we dissect the role of loop 3 in an NADH:quinone oxidoreductase (NQO, UniProt Q9I4V0) from Pseudomonas aeruginosa PA01 in governing substrate binding and catalysis. Previous mechanistic and structural studies proposed that loop 3 fluctuations regulate substrate binding; however, an associated atomic-level understanding of the conformational changes is lacking. We probe the role of loop 3 dynamics in substrate capture and catalysis by mutating conserved P78 to glycine, which perturbs the gate rigidity. Steady-state kinetics with NQO-P78G and NQO-WT at varying concentrations of NADH and coenzyme Q₀ established a 3.5-fold decrease i

SUBMITTER: Dratch BD 

PROVIDER: S-EPMC12781114 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature