A novel mutation at a probable heme-binding ligand in neutrophil cytochrome b558 in atypical X-linked chronic granulomatous disease.
A membrane-bound cytochrome b558, a heterodimer consisting of gp91-phox and p22-phox, is a critical component of the superoxide (O2-)-generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. Chronic granulomatous disease (CGD) is characterized by recurrent bacterial infection caused by a defect of the oxidase. Both subunits are absent from phagocytes in typical X-linked recessive CGD patients who are primarily defective in gp91-phox. We report here an atypical case of X-linked CGD in which neutrophils showed a complete absence of O2--forming NADPH oxidase activity, but a small amount (about 10% of control) of both subunits was detected by immunoblot analysis. Spectrophotometric studies of the neutrophils with a recently developed sensitive method gave no evidence for the heme spectrum in the cytochrome b558, of this CGD. Reverse transcription/polymerase chain reaction and sequence analysis revealed a C to T transition replacing histidine at amino acid position 101 (His101) by tyrosine in gp91-phox. These results provide evidence that His101 of gp91-phox is the one of the heme-binding ligands of cytochrome b558.
Tsuda
M
M
Department of Pediatrics, Nihon University School of Medicine, Tokyo, Japan.
Kaneda
M
M
Sakiyama
T
T
Inana
I
I
Owada
M
M
Kiryu
C
C
Shiraishi
T
T
Kakinuma
K
K
D000293:Adolescent; D003573:Cytochrome b Group / Q000378:metabolism*; D008040:Genetic Linkage; D006105:Granulomatous Disease, Chronic / Q000235:genetics*; D006418:Heme / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D009154:Mutation; D009252:NADPH Dehydrogenase / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D009504:Neutrophils / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D014960:X Chromosome
D003573:Cytochrome b Group; D008024:Ligands; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D010750:Phosphoproteins; D006418:Heme; C036888:cytochrome b558; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C086986:CYBA protein, human; D009252:NADPH Dehydrogenase