Open AccessMultiple Superoxide Dismutases in Agrobacterium tumefaciens : Functional Analysis, Gene Regulation, and Influence on Tumorigenesis
Author(s) -
Panatda Saenkham,
Warawan Eiamphungporn,
Stephen K. Farrand,
Paiboon Vattanaviboon,
Skorn Mongkolsuk
Publication year - 2007
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00960-07
Subject(s) - agrobacterium tumefaciens , biology , superoxide dismutase , menadione , mutant , isozyme , periplasmic space , biochemistry , superoxide , virulence , gene , enzyme , microbiology and biotechnology , transformation (genetics) , escherichia coli
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 ofsod s reveals that the inactivation ofsodBI 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 allsod s contribute at various levels towards the overall menadione resistance level. Sods also have important roles inA. tumefaciens virulence toward a host plant. AsodBI but not asodBII orsodBIII mutant showed marked reduction in its ability to induce tumors on tobacco leaf discs, while the triplesod null mutant is avirulent.