Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.


Logo for

J. Biol. Chem. 278 (7): 4854-4861

© 2003 by The American Society for Biochemistry and Molecular Biology, Inc.

The Guanine Nucleotide Exchange Factor Trio Activates the Phagocyte NADPH Oxidase in the Absence of GDP to GTP Exchange on Rac


Natalia Sigal{ddagger}§, Yara Gorzalczany{ddagger}§, Rive Sarfstein{ddagger}§, Carolyn Weinbaum, Yi Zheng||, , and Edgar Pick{ddagger}**

From the {ddagger}Julius Friedrich Cohnheim-Minerva Center for Phagocyte Research and the Ela Kodesz Institute of Host Defense against Infectious Diseases, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel, the ||Division of Experimental Hematology, Children's Hospital Research Foundation, Cincinnati, Ohio 45229, and the Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710

ABSTRACT Back to Top

Abstract: The superoxide-generating NADPH oxidase complex of phagocytes consists of a membrane-associated flavocytochrome b 559 and four cytosolic components as follows: p47 phox , p67 phox , p40 phox , and the small GTPase Rac (1 or 2). Activation of the oxidase is the result of assembly of the cytosolic components with cytochrome b 559 and can be mimicked in vitro by mixtures of membrane and cytosolic components exposed to an anionic amphiphile, serving as activator. We reported that prenylation of Rac1 endows it with the ability to support oxidase activation in conjunction with p67 phox but in the absence of amphiphile and p47 phox . We now show the following 6 points. 1) The Rac guanine nucleotide exchange factor Trio markedly potentiates oxidase activation by prenylated Rac1-GDP. 2) This occurs in the absence of exogenous GTP or any other source of GTP generation, demonstrating that the effect of Trio does not involve GDP to GTP exchange on Rac1. 3) Trio does not potentiate oxidase activation by prenylated Rac1-GTP, by nonprenylated Rac1-GDP in the presence or absence of amphiphile, and by a prenylated [p67 phox -Rac1] chimera in GDP-bound form. 4) Rac1 mutants defective in the ability to bind Trio or to respond to Trio by nucleotide exchange fail to respond to Trio by enhanced oxidase activation. 5) A Trio mutant with conserved Rac1-binding ability but lacking nucleotide exchange activity fails to enhance oxidase activation. 6) The effect of Trio is mimicked by displacement of Mg2+ from Rac1-GDP. These results reveal the existence of a novel mechanism of Rac activation by a guanine nucleotide exchange factor and suggest that the induction by Trio of a conformational change in Rac1, in the absence of nucleotide exchange, is sufficient for enhancing its effector function.

Received for publication October 28, 2002. Revision received December 2, 2002.

NADPH Oxidase Activation Is Required in Reactive Oxygen Species Generation and Cell Transformation Induced by Hexavalent Chromium.
X. Wang, Y.-O. Son, Q. Chang, L. Sun, J. A. Hitron, A. Budhraja, Z. Zhang, Z. Ke, F. Chen, J. Luo, et al. (2011)
Toxicol. Sci. 123, 399-410
   Abstract »    Full Text »    PDF »
Tripartite Chimeras Comprising Functional Domains Derived from the Cytosolic NADPH Oxidase Components p47phox, p67phox, and Rac1 Elicit Activator-independent Superoxide Production by Phagocyte Membranes: AN ESSENTIAL ROLE FOR ANIONIC MEMBRANE PHOSPHOLIPIDS.
Y. Berdichevsky, A. Mizrahi, Y. Ugolev, S. Molshanski-Mor, and E. Pick (2007)
J. Biol. Chem. 282, 22122-22139
   Abstract »    Full Text »    PDF »
Liposomes Comprising Anionic but Not Neutral Phospholipids Cause Dissociation of Rac(1 or 2){middle dot}RhoGDI Complexes and Support Amphiphile-independent NADPH Oxidase Activation by Such Complexes.
Y. Ugolev, S. Molshanski-Mor, C. Weinbaum, and E. Pick (2006)
J. Biol. Chem. 281, 19204-19219
   Abstract »    Full Text »    PDF »
Assembly of the phagocyte NADPH oxidase complex: chimeric constructs derived from the cytosolic components as tools for exploring structure-function relationships.
A. Mizrahi, Y. Berdichevsky, Y. Ugolev, S. Molshanski-Mor, Y. Nakash, I. Dahan, N. Alloul, Y. Gorzalczany, R. Sarfstein, M. Hirshberg, et al. (2006)
J. Leukoc. Biol. 79, 881-895
   Abstract »    Full Text »    PDF »
Cdc42 Regulates Arsenic-induced NADPH Oxidase Activation and Cell Migration through Actin Filament Reorganization.
Y. Qian, K. J. Liu, Y. Chen, D. C. Flynn, V. Castranova, and X. Shi (2005)
J. Biol. Chem. 280, 3875-3884
   Abstract »    Full Text »    PDF »
Redox Paradox: Insulin Action Is Facilitated by Insulin-Stimulated Reactive Oxygen Species With Multiple Potential Signaling Targets.
B. J. Goldstein, K. Mahadev, and X. Wu (2005)
Diabetes 54, 311-321
   Abstract »    Full Text »    PDF »
Dual Role of Rac in the Assembly of NADPH Oxidase, Tethering to the Membrane and Activation of p67phox: A STUDY BASED ON MUTAGENESIS OF p67phox-Rac1 CHIMERAS.
R. Sarfstein, Y. Gorzalczany, A. Mizrahi, Y. Berdichevsky, S. Molshanski-Mor, C. Weinbaum, M. Hirshberg, M.-C. Dagher, and E. Pick (2004)
J. Biol. Chem. 279, 16007-16016
   Abstract »    Full Text »    PDF »

To Advertise     Find Products

Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882