Activation of H+ conductance in neutrophils requires assembly of components of the respiratory burst oxidase but not its redox function

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 granulomatou...

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Bibliographic Details
Published in:The Journal of clinical investigation 1994-04, Vol.93 (4), p.1770-1775
Main Authors: NANDA, A, CURNUTTE, J. T, GRINSTEIN, S
Format: Article
Language:English
Subjects:
Biological and medical sciences
Female
Granulomatous Disease, Chronic - metabolism
Humans
Ion Transport
Male
Medical sciences
NADH, NADPH Oxidoreductases - physiology
NADPH Oxidases
Neutrophils - metabolism
Oxidation-Reduction
Point Mutation
Protons
Respiratory Burst
Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis
Tetradecanoylphorbol Acetate - pharmacology
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Summary: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.
ISSN:0021-9738
1558-8238
DOI:10.1172/JCI117162