Multiple superoxide dismutases in Agrobacterium tumefaciens: functional analysis, gene regulation, and influence on tumorigenesis.
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.
Saenkham
Panatda
P
Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.
Eiamphungporn
Warawan
W
Farrand
Stephen K
SK
Vattanaviboon
Paiboon
P
Mongkolsuk
Skorn
S
D016960:Agrobacterium tumefaciens / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D016877:Oxidants / Q000493:pharmacokinetics; D018515:Plant Leaves / Q000382:microbiology; D013482:Superoxide Dismutase / Q000235:genetics* / Q000502:physiology*; D014026:Nicotiana / Q000382:microbiology; D014774:Virulence / Q000235:genetics; D024483:Vitamin K 3 / Q000494:pharmacology
D001426:Bacterial Proteins; D016877:Oxidants; D024483:Vitamin K 3; C087504:SodB protein, Bacteria; D013482:Superoxide Dismutase