title: The gp91phox component of NADPH oxidase is not the voltage-gated proton channel in phagocytes, but it helps.
abstract: During the "respiratory burst," the NADPH oxidase complex of phagocytes produces reactive oxygen species that kill bacteria and other invaders (Babior, B. M. (1999) Blood 93, 1464-1476). Electron efflux through NADPH oxidase is electrogenic (Henderson, L. M., Chappell, J. B., and Jones, O. T. G. (1987) Biochem. J. 246, 325-329) and is compensated by H(+) efflux through proton channels that reportedly are contained within the gp91(phox) subunit of NADPH oxidase. To test whether gp91(phox) functions as a proton channel, we studied H(+) currents in granulocytes from X-linked chronic granulomatous disease patients lacking gp91(phox) (X-CGD), the human myelocytic PLB-985 cell line, PLB-985 cells in which gp91(phox) was knocked out by gene targeting (PLB(KO)), and PLB-985 knockout cells re-transfected with gp91(phox) (PLB(91)). H(+) currents in unstimulated PLB(KO) cells had amplitude and gating kinetics similar to PLB(91) cells. Furthermore, stimulation with the phorbol ester phorbol 12-myristate 13-acetate increased H(+) currents to a similar extent in X-CGD, PLB(KO), and PLB(91) cells. Thus, gp91(phox) is not the proton channel in unstimulated phagocytes and does not directly mediate the increase of proton conductance during the respiratory burst. Changes in H(+) channel gating kinetics during NADPH oxidase activity are likely crucial to the activation of H(+) flux during the respiratory burst.
authors.affiliation: Department of Molecular Biophysics and Physiology, Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612, USA. tdecours@rush.edu
authors.forename: T E
authors.initials: TE
authors.lastname: DeCoursey
authors.forename: V V
authors.initials: VV
authors.lastname: Cherny
authors.forename: D
authors.initials: D
authors.lastname: Morgan
authors.forename: B Z
authors.initials: BZ
authors.lastname: Katz
authors.forename: M C
authors.initials: MC
authors.lastname: Dinauer
mesh_terms: D002273:Carcinogens; D002460:Cell Line; D004594:Electrophysiology; D006105:Granulomatous Disease, Chronic / Q000235:genetics; D006801:Humans; D006859:Hydrogen / Q000378:metabolism; D007477:Ions; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000502:physiology*; D009154:Mutation; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000737:chemistry*; D010586:Phagocytes / Q000378:metabolism*; D011522:Protons; D016897:Respiratory Burst; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism; D019076:Transgenes
chemical_list: D002273:Carcinogens; D007477:Ions; D008562:Membrane Glycoproteins; D011522:Protons; D006859:Hydrogen; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D013755:Tetradecanoylphorbol Acetate