N-oxide metabolism IV

Sensing and detoxification of nitric oxide is discussed as a protection mechanism in some pathogenic bacteria. Comparative analysis of baterial genomes revealed that a quinol-dependent NO reductase (qNOR) termed NorB, first discovered in the soil bacterium Ralstonia eutropha, is widely distributed among pathogenic bacteria. In R. eutropha, formation of NorB is controlled by an NO-sensing transcriptional activator NorR. The NorR-NorB system is used as a model to examine NO-dependent signal transduction in prokaryotes, for which many aspects are still unknown. In the framework of this study, we will examine both signal reception by NorR and binding of NorR to the DNA. Putative cofactors in NorR will be identified, and the role of the norA gene, which is coexpressed with norB, will be clarified.
An intriguing feature of qNor enzymes is an N-terminal extension with unknown function. Molecular and biochemical analysis of NorB will focus on this extension. Site-directed mutagenesis and expression of subforms will shed light on the electron donor and other putative interaction partners of NorB.