The mechanism of catalysis by type-II NADH:quinone oxidoreductases

• DOI: 10.1038/srep40165
• Publication Date: 2017-01-09T10:05:05Z
• Authors: James N. Blaza; Hannah R. Bridges; David Aragão; Elyse A. Dunn; Adam Heikal; Gregory M. Cook; Yoshio Nakatani; Judy Hirst
• Keywords: 0301 basic medicine; 570; Bacillales; Binding Sites; 572; Dinitrocresols; Article; Catalysis; Kinetics; 03 medical and health sciences; Quinone Reductases; Reactive Oxygen Species; Protein Binding

Abstract Type II NADH:quinone oxidoreductase (NDH-2) is central to the respiratory chains of many organisms. It not present in mammals so may be exploited as an antimicrobial drug target or used a substitute for dysfunctional complex I neuromuscular disorders. NDH-2 single-subunit monotopic membrane protein with just flavin cofactor, yet no consensus exists on its mechanism. Here, we use steady-state and pre-steady-state kinetics combined mutagenesis structural studies determine mechanism from Caldalkalibacillus thermarum . We show that two substrate reactions occur independently, at different sites, regardless occupancy partner site. conclude reaction pathway determined stochastically, by substrate/product concentrations dissociation constants, can follow either ping-pong ternary This mechanistic versatility provides unified explanation all extant data new foundation development therapeutic strategies.