Journal Article

Enzymology and molecular biology of prokaryotic sulfite oxidation

Ulrike Kappler and Christiane Dahl

in FEMS Microbiology Letters

Volume 203, issue 1, pages 1-9
Published in print September 2001 |
Published online January 2006 | e-ISSN: 1574-6968 | DOI:

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Despite its toxicity, sulfite plays a key role in oxidative sulfur metabolism and there are even some microorganisms which can use it as sole electron source. Sulfite is the main intermediate in the oxidation of sulfur compounds to sulfate, the major product of most dissimilatory sulfur-oxidizing prokaryotes. Two pathways of sulfite oxidation are known: (1) direct oxidation to sulfate catalyzed by a sulfite:acceptor oxidoreductase, which is thought to be a molybdenum-containing enzyme; (2) indirect oxidation under the involvement of the enzymes adenylylsulfate (APS) reductase and ATP sulfurylase and/or adenylylsulfate:phosphate adenylyltransferase with APS as an intermediate. The latter pathway allows substrate phosphorylation and occurs in the bacterial cytoplasm. Direct oxidation appears to have a wider distribution; however, a redundancy of pathways has been described for diverse photo- or chemotrophic, sulfite-oxidizing prokaryotes. In many pro- and also eukaryotes sulfite is formed as a degradative product from molecules containing sulfur as a heteroatom. In these organisms detoxification of sulfite is generally achieved by direct oxidation to sulfate.

Keywords: sulfite oxidation; bacteria; adenylylsulfate (APS) reductase; sulfite dehydrogenase; sulfite:acceptor oxidoreductase

Journal Article.  5760 words.  Illustrated.

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