PMID:19054099

Citation	Saenkham, P, Utamapongchai, S, Vattanaviboon, P and Mongkolsuk, S (2008) Agrobacterium tumefaciens iron superoxide dismutases have protective roles against singlet oxygen toxicity generated from illuminated Rose Bengal. FEMS Microbiol. Lett. 289:97-103
Abstract	Singlet oxygen is a highly reactive form of molecular oxygen that is harmful to biological systems. Here, the role of three iron-containing superoxide dismutase (sodB) genes is clearly shown in protecting Agrobacterium tumefaciens against singlet oxygen toxicity. A sodBI mutant was more sensitive to singlet oxygen than both wild-type bacteria and a double sodBII-sodBIII mutant strain. Moreover, a sodBI-sodBII double mutant had higher sensitivity to singlet oxygen than a single sodBI mutant, although the double mutant was comparable to a sodB null mutant. High-level expression of sodBI and sodBII fully complemented the singlet oxygen hypersensitivity phenotype of the sodB null mutant, while high-level expression of sodBIII encoding a periplasmic SOD only partially restored the phenotype. Taken together, our data suggest that SodBI and SodBII have novel protective roles against singlet oxygen toxicity through unknown mechanisms.
Links	PubMed Online version:10.1111/j.1574-6968.2008.01382.x
Keywords	Agrobacterium tumefaciens/drug effects; Agrobacterium tumefaciens/enzymology; Agrobacterium tumefaciens/growth & development; Culture Media; Gene Expression Regulation, Bacterial; Isoenzymes/genetics; Isoenzymes/metabolism; Light; Mutation; Rose Bengal/metabolism; Singlet Oxygen/metabolism; Singlet Oxygen/toxicity; Superoxide Dismutase/genetics; Superoxide Dismutase/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRT5:Q7CVB7		GO:0004784: superoxide dismutase activity	ECO:0000315:		F		The role of three iron-containing superoxide dismutase (sodB) genes is shown to protect Agrobacterium tumefaciens against singlet oxygen toxicity in both exponential and stationary growth phases. A sodBI mutant was more sensitive to singlet oxygen than both wild-type bacteria and a double sodBII–sodBIII mutant strain. A sodBI–sodBII double mutant had higher sensitivity to singlet oxygen than a single sodBI mutant, although the double mutant was similar to a sodB null mutant (Figure 2). Cells in the stationary phase were shown to be more vulnerable to damage caused by singlet oxygen than cells in the exponential growth phase. Although SOD exerts a protective effect against both super- oxide anions and singlet oxygen, the response of A. tumefaciens to singlet oxygen was different from the response to super- oxide anion. The avirulent phenotype of the SOD null mutant could be due to the inability to cope with superoxide anions and singlet oxygen generated from plant active defense response to microbial invasion.	complete
AGRT5:Q7CVP7		GO:0004784: superoxide dismutase activity	ECO:0000315:		F		Figure 1 supports the function of superoxide dismutase	complete
AGRT5:A9CJS9		GO:0004784: superoxide dismutase activity	ECO:0000315:		F		Fig. 1 shows decreased resistance to toxicitiy of mutated sodBI.	complete

References

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