title: Activation of H+ conductance in neutrophils requires assembly of components of the respiratory burst oxidase but not its redox function.
abstract: In phagocytes, superoxide generation by the NADPH oxidase is accompanied by metabolic acid production. Cytoplasmic acidification during this metabolic burst is prevented by a combination of H+ extrusion mechanisms, including a unique H+ conductance. NADPH oxidase is deficient in chronic granulomatous disease (CGD) patients. The burst of acid production is absent in CGD patients lacking the 47-kD (p47-phox) or the 91-kD (gp91-phox) subunits of the oxidase. Activation of the H+ conductance is also defective in these patients suggesting that (a) the oxidase itself undertakes H+ translocation or (b) oxidase assembly is required to stimulate a separate H+ conducting entity. To discern between these possibilities, three rare forms of CGD were studied. In neutrophils expressing nonfunctional cytochrome b, the conductance was activated to near-normal levels, implying that functional oxidase is not required to activate H+ extrusion. CGD cells expressing diminished amounts of cytochrome displayed H+ conductance approaching normal levels, suggesting that the oxidase itself does not translocate H+. Finally, the conductance was only partially inhibited in patients lacking the 67-kD subunit, indicating that this component is not essential for stimulation of H+ transport. We propose that normal assembly of the oxidase subunits is required for optimal activation of a closely associated but distinct H+ conducting entity.
authors.affiliation: Division of Cell Biology, Hospital for Sick Children, Toronto, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Nanda
authors.forename: J T
authors.initials: JT
authors.lastname: Curnutte
authors.forename: S
authors.initials: S
authors.lastname: Grinstein
mesh_terms: D005260:Female; D006105:Granulomatous Disease, Chronic / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport; D008297:Male; D009247:NADH, NADPH Oxidoreductases / Q000502:physiology*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000378:metabolism*; D010084:Oxidation-Reduction; D017354:Point Mutation; D011522:Protons; D016897:Respiratory Burst; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D011522:Protons; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D013755:Tetradecanoylphorbol Acetate