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Journal of Bacteriology, December 2007, p. 8807-8817, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.00960-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Multiple Superoxide Dismutases in Agrobacterium tumefaciens: Functional Analysis, Gene Regulation, and Influence on Tumorigenesis{triangledown}

Panatda Saenkham,1 Warawan Eiamphungporn,1,{dagger} Stephen K. Farrand,2 Paiboon Vattanaviboon,3 and Skorn Mongkolsuk1,3,4*

Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand,3 Department of Biotechnology,1 Centre of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok 10400, Thailand,4 Department of Microbiology, University of Illinois at Urbana-Campaign, Urbana, Illinois 618012

Received 18 June 2007/ Accepted 25 September 2007

Agrobacterium tumefaciens possesses three iron-containing superoxide dismutases (FeSods) encoded by distinct genes with differential expression patterns. SodBI and SodBII are cytoplasmic isozymes, while SodBIII is a periplasmic isozyme. sodBI is expressed at a high levels throughout all growth phases. sodBII expression is highly induced upon exposure to superoxide anions in a SoxR-dependent manner. sodBIII is expressed only during stationary phase. Analysis of the physiological function of sods reveals that the inactivation of sodBI markedly reduced levels of resistance to a superoxide generator, menadione. A mutant lacking all three Sod enzymes is the most sensitive to menadione treatment, indicating that all sods contribute at various levels towards the overall menadione resistance level. Sods also have important roles in A. tumefaciens virulence toward a host plant. A sodBI but not a sodBII or sodBIII mutant showed marked reduction in its ability to induce tumors on tobacco leaf discs, while the triple sod null mutant is avirulent.

* Corresponding author. Mailing address: Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand. Phone: (662) 574 0623, ext. 3816. Fax: (662) 574 2027. E-mail: skorn{at}cri.or.th

{triangledown} Published ahead of print on 5 October 2007.

{dagger} Present address: Department of Microbiology, Cornell University, Ithaca, NY 14853-8101.

Journal of Bacteriology, December 2007, p. 8807-8817, Vol. 189, No. 24
0021-9193/07/$08.00+0     doi:10.1128/JB.00960-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

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  • Lee, L.-Y., Gelvin, S. B. (2008). T-DNA Binary Vectors and Systems. Plant Physiol. 146: 325-332 [Full Text]  


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