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Journal of Bacteriology, February 2009, p. 1035-1043, Vol. 191, No. 3
0021-9193/09/$08.00+0     doi:10.1128/JB.01293-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Functional Roles of arcA, etrA, Cyclic AMP (cAMP)-cAMP Receptor Protein, and cya in the Arsenate Respiration Pathway in Shewanella sp. Strain ANA-3{triangledown} ,{dagger}

Julie N. Murphy,1 K. James Durbin,2 and Chad W. Saltikov1*

Department of Microbiology and Environmental Toxicology,1 Department of Biomolecular Engineering, University of California, Santa Cruz, 1156 High Street, Santa Cruz, California 950642

Received 15 September 2008/ Accepted 25 November 2008

Microbial arsenate respiration can enhance arsenic release from arsenic-bearing minerals—a process that can cause arsenic contamination of water. In Shewanella sp. strain ANA-3, the arsenate respiration genes (arrAB) are induced under anaerobic conditions with arsenate and arsenite. Here we report how genes that encode anaerobic regulator (arcA and etrA [fnr homolog]) and carbon catabolite repression (crp and cya) proteins affect arsenate respiration in ANA-3. Transcription of arcA, etrA, and crp in ANA-3 was similar in cells grown on arsenate and cells grown under aerobic conditions. ANA-3 strains lacking arcA and etrA showed minor to moderate growth defects, respectively, with arsenate. However, crp was essential for growth on arsenate. In contrast to the wild-type strain, arrA was not induced in the crp mutant in cultures shifted from aerobic to anaerobic conditions containing arsenate. This indicated that cyclic AMP (cAMP)-cyclic AMP receptor (CRP) activates arr operon transcription. Computation analysis for genome-wide CRP binding motifs identified a putative binding motif within the arr promoter region. This was verified by electrophoretic mobility shift assays with cAMP-CRP and several DNA probes. Lastly, four putative adenylate cyclase (cya) genes were identified in the genome. One particular cya-like gene was differentially expressed under aerobic versus arsenate respiration conditions. Moreover, a double mutant lacking two of the cya-like genes could not grow with arsenate as a terminal electron acceptor; exogenous cAMP could complement growth of the double cya mutant. It is concluded that the components of the carbon catabolite repression system are essential to regulating arsenate respiratory reduction in Shewanella sp. strain ANA-3.

* Corresponding author. Mailing address: Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064. Phone: (831) 459-5520. Fax: (831) 459-3524. E-mail: saltikov{at}etox.ucsc.edu

{triangledown} Published ahead of print on 5 December 2008.

{dagger} Supplemental material for this article may be found at http://jb.asm.org/.

Journal of Bacteriology, February 2009, p. 1035-1043, Vol. 191, No. 3
0021-9193/09/$08.00+0     doi:10.1128/JB.01293-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Murphy, J. N., Saltikov, C. W. (2009). The ArsR Repressor Mediates Arsenite-Dependent Regulation of Arsenate Respiration and Detoxification Operons of Shewanella sp. Strain ANA-3. J. Bacteriol. 191: 6722-6731 [Abstract] [Full Text]  
  • Charania, M. A., Brockman, K. L., Zhang, Y., Banerjee, A., Pinchuk, G. E., Fredrickson, J. K., Beliaev, A. S., Saffarini, D. A. (2009). Involvement of a Membrane-Bound Class III Adenylate Cyclase in Regulation of Anaerobic Respiration in Shewanella oneidensis MR-1. J. Bacteriol. 191: 4298-4306 [Abstract] [Full Text]  


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