A Fission Yeast Gene for Mitochondrial Sulfide Oxidation*
- From the ‡Plant Gene Expression Center, U. S. Department of Agriculture-Agricultural Research Service, Albany, California 94710 and the §Department of Plant and Microbial Biology, University of California, Berkeley, California 94720
Abstract
A cadmium-hypersensitive mutant of the fission yeast Schizosaccharomyces pombe was found to accumulate abnormally high levels of sulfide. The gene required for normal regulation of sulfide levels, hmt2 +, was cloned by complementation of the cadmium-hypersensitive phenotype of the mutant. Cell fractionation and immunocytochemistry indicated that HMT2 protein is localized to mitochondria. Sequence analysis revealed homology between HMT2 and sulfide dehydrogenases from photosynthetic bacteria. HMT2 protein, produced in and purified from Escherichia coli, was soluble, bound FAD, and catalyzed the reduction of quinone (coenzyme Q2) by sulfide. HMT2 activity was also detected in isolated fission yeast mitochondria. We propose that HMT2 functions as a sulfide:quinone oxidoreductase. Homologous enzymes may be widespread in higher organisms, as sulfide-oxidizing activities have been described previously in animal mitochondria, and genes of unknown function, but with similarity to hmt2 +, are present in the genomes of flies, worms, rats, mice, and humans.
Footnotes
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↵* This work was supported by U. S. Department of Energy Grant EM96–55278 (to D. W. O.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AF042283.
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↵¶ Present address: MicroGenomics Inc., 11211 Sorrento Valley Rd., San Diego, CA 92121.
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↵‖ To whom correspondence should be addressed: Plant Gene Expression Center, USDA-ARS, 800 Buchanan St., Albany, CA 94710. Tel.: 510-559-5909; Fax: 510-559-5678; Email: ow{at}pgec.ars.usda.gov.
- Abbreviations:
- MNNG
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N-methyl-N′-nitro-N-nitrosoguanidine
- DTNB
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5,5′-dithiobis(2-nitrobenzoic acid)
- CHAPS
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3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid
- kb
-
kilobase(s)
- IPTG
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isopropyl-1-thio-β-d-galactopyranoside
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- Received December 2, 1998.
- Revision received February 24, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
