title: Distribution, diversity, and activities of sulfur dioxygenases in heterotrophic bacteria.
abstract: Sulfur oxidation by chemolithotrophic bacteria is well known; however, sulfur oxidation by heterotrophic bacteria is often ignored. Sulfur dioxygenases (SDOs) (EC 1.13.11.18) were originally found in the cell extracts of some chemolithotrophic bacteria as glutathione (GSH)-dependent sulfur dioxygenases. GSH spontaneously reacts with elemental sulfur to generate glutathione persulfide (GSSH), and SDOs oxidize GSSH to sulfite and GSH. However, SDOs have not been characterized for bacteria, including chemolithotrophs. The gene coding for human SDO (human ETHE1 [hETHE1]) in mitochondria was discovered because its mutations lead to a hereditary human disease, ethylmalonic encephalopathy. Using sequence analysis and activity assays, we discovered three subgroups of bacterial SDOs in the proteobacteria and cyanobacteria. Ten selected SDO genes were cloned and expressed in Escherichia coli, and the recombinant proteins were purified. The SDOs used Fe(2+) for catalysis and displayed considerable variations in specific activities. The wide distribution of SDO genes reveals the likely source of the hETHE1 gene and highlights the potential of sulfur oxidation by heterotrophic bacteria.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, People's Republic of China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Liu
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Xin
authors.forename: Luying
authors.initials: L
authors.lastname: Xun
mesh_terms: D003001:Cloning, Molecular; D016000:Cluster Analysis; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D049308:Dioxygenases / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D014644:Genetic Variation; D052836:Heterotrophic Processes; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D020560:Proteobacteria / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013455:Sulfur / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D013455:Sulfur; D007501:Iron; D049308:Dioxygenases; C477654:sulfur dioxygenase