Cell-free translocation of recombinant p47-phox, a component of the neutrophil NADPH oxidase: effects of guanosine 5'-O-(3-thiotriphosphate), diacylglycerol, and an anionic amphiphile

• Published in: Biochemistry (Easton) Vol. 31; no. 10; pp. 2765 - 2774
• Main Authors: Tyagi, Shiv Raj, Neckelmann, Nicolas, Uhlinger, David J, Burnham, David N, Lambeth, J. David
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17.03.1992
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Anions; Autoradiography; Base Sequence; Biological and medical sciences; Cell Membrane - enzymology; Cell-Free System; Cytochrome b Group - genetics; Cytochrome b Group - metabolism; Diglycerides - pharmacology; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Guanosine 5'-O-(3-Thiotriphosphate) - pharmacology; Molecular Sequence Data; NADH, NADPH Oxidoreductases - metabolism; NADPH Oxidases; Neutrophils - enzymology; Oxidoreductases; Plasmids; Protein Biosynthesis; Superoxides - metabolism; Transcription, Genetic; Human; GTP; Enzyme; Diglyceride; Granulocyte; Activation; In vitro; Anionic surfactant; Analog; Plasma membrane; Molecular association; Neutrophil; Cell free system
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00125a017

We reported previously that diacylglycerol (diC8) and GTP gamma S synergize with an anionic amphiphile such as sodium dodecyl sulfate (SDS) to produce high rates of superoxide generation in a cell-free system consisting of neutrophil plasma membrane plus cytosol [Burnham, D. N., Uhlinger, D. J., & Lambeth, J. D. (1990) J. Biol. Chem. 265, 17550-17559]. Here we investigate the effects of these activating factors on the plasma membrane association in an in vitro translated radiolabeled recombinant p47-phox protein. Apparent translocation, assayed by cosedimentation with plasma membranes, required the presence of excess cytosol and an anionic amphiphile, was enhanced by both GTP gamma S and diC8, and was inhibited by high salt, correlating qualitatively with activation; up to 70% cosedimentation was observed with the combination of activators (compared with less than 20% in their absence). Similar results were obtained using heat-inactivated cytosol, wherein another oxidase component, p67-phox, has been inactivated. Unexpectedly, from 50 to 80% of the apparent translocation occurred in the absence of membranes, indicating that protein aggregation accounted for a significant part of the observed translocation. Nevertheless, the percent translocation was increased in all cases by the presence of membranes, indicating some degree of protein-membrane interaction. While a control in vitro translated protein failed to translocate, cosedimentation of p47-phox occurred equally well when red blood cell or neutrophil plasma membranes lacking cytochrome b558 were used. Also, the peptide RGVHFIF, which is contained within the C-terminus of the large subunit of cytochrome b558, failed to inhibit translocation/aggregation of p47-phox, despite its ability to inhibit cell-free activation of the oxidase. The data are consistent with the following: (a) SDS, diC8, and GTP gamma S all act on cytosolic components to alter protein-protein and/or protein-membrane associations, and these changes are necessary (but not sufficient) for activation; (b) these altered associations are likely to function by increasing the local concentration of p47-phox and other components at the plasma membrane; (c) a high background of nonspecific associations in the cell-free activation system is likely to obscure any specific, functionally relevant associations (e.g., with cytochrome b558); and (d) the mechanism of translocation in the cell-free system differs from that seen in intact neutrophils.