Role for the first SH3 domain of p67phox in activation of superoxide-producing NADPH oxidases.
The membrane-bound NADPH oxidase in phagocytes, gp91(phox) (a.k.a. Nox2), produces superoxide, a precursor of microbicidal oxidants, thereby playing a crucial role in host defense. Activation of gp91(phox)/Nox2 requires assembly with the cytosolic proteins p67(phox) and p47(phox), each containing two SH3 domains. Although the C-terminal SH3 domain of p67(phox) is responsible for binding to p47(phox), little is known about the role for the first (N-terminal) SH3 domain [SH3(N)]. Here we show that truncation of p67(phox)-SH3(N), but not substitution of arginine for the invariant residue Trp-277 in SH3(N), results in an impaired activation of gp91(phox)/Nox2. The impairment is overcome by higher expression of an SH3(N)-defective p67(phox) in cells, suggesting that SH3(N) primarily increases the affinity of p67(phox) for the oxidase complex. On the other hand, p67(phox)-SH3(N) is not involved in activation of Nox1 and Nox3, closely-related homologues of gp91(phox)/Nox2. Thus p67(phox)-SH3(N) specifically functions in gp91(phox)/Nox2 activation probably via facilitating oxidase assembly.
Maehara
Yuichi
Y
Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Miyano
Kei
K
Sumimoto
Hideki
H
D019943:Amino Acid Substitution; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014364:Tryptophan / Q000235:genetics / Q000378:metabolism; D018909:src Homology Domains
D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; D014364:Tryptophan; D001120:Arginine; C056558:CYBB protein, human; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C402799:NOX1 protein, human; C431570:Nox3 protein, human