Fe/Mn superoxide dismutase-encoding gene in Paracoccus denitrificans is induced by azide and expressed independently of the FNR-type regulators
- 100 Downloads
Paracoccus denitrificans cells undergo changes in protein composition upon exposure to azide, a known activator of the fumarate–nitrate reduction (FNR)-type transcription factor NarR. One of the most prominent protein species inducible by azide is a Fe/Mn-family superoxide dismutase (SOD). Azide induces SOD at protein, mRNA transcript, and enzyme activity levels in the aerobically growing cells. Since SOD expression remains unaffected in the fnrP-, nnr-, and narR-mutant strains, we postulate a mechanism independent of the known FNR-type regulators but involving a redox signal arising from the respiratory chain.
KeywordsAzide Nitrate Reductase Terminal Oxidase Paracoccus Denitrificans Superoxide Free Radical
The authors thank Dr. R. van Spanning (Vrije Universiteit, Amsterdam) who kindly provided with the FnrP-, NNR-, and NarR-mutant strains. The work was supported by grants nos. 203/07/P0471 and P304/10/0868 of the Czech Science Foundation and by the Ministry of Education, Youth and Sports of the Czech Republic (project MSM0021622413).
- Lee YY, Shearer N, Spiro S (2006) Transcription factor NNR from Paracoccus denitrificans is a sensor of both nitric oxide and oxygen: isolation of nnr* alleles encoding effector-independent proteins and evidence for a hem-based sensing mechanism. Microbiology 152:1461–1470PubMedCrossRefGoogle Scholar