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Respiratory arsenate reductase as a bidirectional enzyme

Biochemical and Biophysical Research Communications

By:
, , , , , and
DOI: 10.1016/j.bbrc.2009.03.045

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Abstract

The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative respiratory arsenate reductase (Arr). Here we show that one homolog is expressed under chemolithoautotrophic conditions and exhibits both arsenite oxidase and arsenate reductase activity. We also demonstrate that Arr from two arsenate respiring bacteria, Alkaliphilus oremlandii and Shewanella sp. strain ANA-3, is also biochemically reversible. Thus Arr can function as a reductase or oxidase. Its physiological role in a specific organism, however, may depend on the electron potentials of the molybdenum center and [Fe–S] clusters, additional subunits, or constitution of the electron transfer chain. This versatility further underscores the ubiquity and antiquity of microbial arsenic metabolism.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Respiratory arsenate reductase as a bidirectional enzyme
Series title:
Biochemical and Biophysical Research Communications
DOI:
10.1016/j.bbrc.2009.03.045
Volume
382
Issue:
2
Year Published:
2009
Language:
English
Publisher:
Elsevier
Description:
5 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biochemical and Biophysical Research Communications
First page:
298
Last page:
302