Oxidative stress sensors in pathogenic bacteria

Desulfovibrio vulgaris PerR. This bacterial repressor has a structural metal center with zinc and an active site containing iron. In the presence of these two metals and hydrogen peroxide it adopts an open conformation unable to bind to DNA, allowing the expression of oxidative stress protection enzymes, such as catalase or bacterioferritins. Work has involved cloning and over-expressing the protein in Escherichia coli, preliminary spectroscopic characterization and development of a DNA binding activity assay.

Staphylococcus aureus AirSR. AirSR is a [2Fe-2S] containing two-component system (TCS) recently isolated from S. aureus. TCS frequently control the expression of virulence genes in pathogenic bacteria. AirS subunit is a kinase, that catalyses the autophosphorylation of a histidine residue, and subsquently transfers the phosphoryl group to an aspartate residue of AirR. AirS's kinase activity was inactivated by strong oxidants such as NO and H2O2, or prolonged exposure to oxygen.

Study of a hemic protein, isolated from the bacteria Shewanella baltica, which binds molecular oxygen and has a highly unusual axial coordination. Spectroscopic characterization of the protein both with and without bound oxygen and investigating its physiological role in the bacteria is currently being done.