Characterization of an alternative oxidase activity of Histoplasma capsulatum.
Histoplasma capsulatum possesses a branched mitochondrial electron transport chain, with both cyanide-sensitive and -insensitive oxygen-consuming activities. The latter, carried out by a single subunit enzyme termed 'alternative oxidase', is the focus of this report. AOX1 cDNA clones were isolated and direct evidence that the cDNA ORF encodes functional alternative oxidase is reported. Also reported are the generation of an antiserum to the AOX1 protein product, and specific detection in vivo of the mRNA and protein products of the AOX1 gene. Finally, initial studies of regulation of H. capsulatum AOX1 gene expression demonstrated that RNA abundance was increased after hydrogen peroxide-mediated oxidative stress and after inhibition of mitochondrial electron transport enzymes with antimycin A or sodium cyanide. This pattern of regulation is consistent with the hypothesis that alternative oxidase contributes to survival of H. capsulatum after oxidative or metabolic stress and may be important for virulence of this pathogenic organism. The GenBank Accession Nos for the cDNA sequences reported in this paper are AF133236, AF133237 (AOX1).
Johnson
Clayton H
CH
Department of Geriatrics, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA. johnsonclaytonh@uams.edu
Prigge
Jonathan T
JT
Warren
Aaron D
AD
McEwen
Joan E
JE
D000595:Amino Acid Sequence; D000968:Antimycin A / Q000494:pharmacology; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D003486:Cyanides / Q000378:metabolism / Q000494:pharmacology; D004579:Electron Transport; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006658:Histoplasma / Q000201:enzymology* / Q000235:genetics; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010940:Plant Proteins; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D000099188:Alternative Oxidase
D000968:Antimycin A; D003486:Cyanides; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D012331:RNA, Fungal; D011994:Recombinant Proteins; D000099188:Alternative Oxidase