Arsenite Oxidase from Ralstonia sp. 22

• Published in: The Journal of biological chemistry Vol. 285; no. 27; pp. 20433 - 20441
• Main Authors: Lieutaud, Aurélie, van Lis, Robert, Duval, Simon, Capowiez, Line, Muller, Daniel, Lebrun, Régine, Lignon, Sabrina, Fardeau, Marie-Laure, Lett, Marie-Claire, Nitschke, Wolfgang, Schoepp-Cothenet, Barbara
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.07.2010
• Subjects: Achromobacter; Arsenite Oxidase; Bacterial Metabolism; Bioenergetics; Cytochrome c; Electron Transfer; Enzyme Kinetics; Enzyme Purification; Evolution; Ralstonia; Cytochrome c; Enzyme Purification; Bioenergetics; Bacterial Metabolism; Electron Transfer; Arsenite Oxidase; Evolution; Enzyme Kinetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.113761

We characterized the aro arsenite oxidation system in the novel strain Ralstonia sp. 22, a β-proteobacterium isolated from soil samples of the Salsigne mine in southern France. The inducible aro system consists of a heterodimeric membrane-associated enzyme reacting with a dedicated soluble cytochrome c554. Our biochemical results suggest that the weak association of the enzyme to the membrane probably arises from a still unknown interaction partner. Analysis of the phylogeny of the aro gene cluster revealed that it results from a lateral gene transfer from a species closely related to Achromobacter sp. SY8. This constitutes the first clear cut case of such a transfer in the Aro phylogeny. The biochemical study of the enzyme demonstrates that it can accommodate in vitro various cytochromes, two of which, c552 and c554, are from the parent species. Cytochrome c552 belongs to the sox and not the aro system. Kinetic studies furthermore established that sulfite and sulfide, substrates of the sox system, are both inhibitors of Aro activity. These results reinforce the idea that sulfur and arsenic metabolism are linked.