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Genetic identification of a respiratory arsenate reductase

Saltikov, Chad W. and Newman, Dianne K. (2003) Genetic identification of a respiratory arsenate reductase. Proceedings of the National Academy of Sciences of the United States of America, 100 (19). pp. 10983-10988. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:SALpnas03

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Abstract

For more than a decade, it has been recognized that arsenate [H2AsO41-; As(V)] can be used by microorganisms as a terminal electron acceptor in anaerobic respiration. Given the toxicity of arsenic, the mechanistic basis of this process is intriguing, as is its evolutionary origin. Here we show that a two-gene cluster (arrAB; arsenate respiratory reduction) in the bacterium Shewanella sp. strain ANA-3 specifically confers respiratory As(V) reductase activity. Mutants with in-frame deletions of either arrA or arrB are incapable of growing on As(V), yet both are able to grow on a wide variety of other electron acceptors as efficiently as the wild-type. Complementation by the wild-type sequence rescues the mutants' ability to respire As(V). arrA is predicted to encode a 95.2-kDa protein with sequence motifs similar to the molybdenum containing enzymes of the dimethyl sulfoxide reductase family. arrB is predicted to encode a 25.7-kDa iron-sulfur protein. arrA and arrB comprise an operon that contains a twin arginine translocation (Tat) motif in ArrA (but not in ArrB) as well as a putative anaerobic transcription factor binding site upstream of arrA, suggesting that the respiratory As(V) reductase is exported to the periplasm via the Tat pathway and under anaerobic transcriptional control. These genes appear to define a new class of reductases that are specific for respiratory As(V) reduction.


Item Type:Article
Additional Information:Copyright © 2003 by the National Academy of Sciences. Communicated by Douglas C. Rees, California Institute of Technology, Pasadena, CA, July 14, 2003 (received for review May 1, 2003). Published online before print August 25, 2003, 10.1073/pnas.1834303100 We thank John Stolz for helpful discussions and access to unpublished sequence data for Bacillus selenitrireducans. Jared Leadbetter and members of the Newman laboratory provided constructive criticism of the manuscript. This study was made possible by grants from the Luce Foundation and the Packard Foundation (to D.K.N.). This material is based on work supported by the National Science Foundation under a grant awarded in 2002 (to C.W.S.). Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. AY271310).
Subject Keywords:escherichia-coli, SP-NOV, chrysiogenes-arsenatis, molecular analysis, bacterium, system, desulfitobacterium, purification, sequence, proteins
Record Number:CaltechAUTHORS:SALpnas03
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:SALpnas03
Alternative URL:http://dx.doi.org/10.1073/pnas.1834303100
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1008
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:01 Dec 2005
Last Modified:14 Nov 2014 19:18

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