Screening of nitrosative stress resistance genes in Coxiella burnetii: Involvement of nucleotide excision repair.

Coxiella burnetii, an obligate intracellular Gram-negative bacterium, is the etiological agent of Q fever. This work takes advantage of a hypersensitive Escherichia coli genetic system to identify genes involved in resistance to nitrosative stress imposed by reactive nitrogen intermediates. Among the ten candidate genes identified, the transposase, UvrB and DNA topoisomerase IV are involved in DNA transaction; the sigma-32 factor and the putative DNA-binding protein may be involved in transcriptional regulation; IF-2 is involved in protein translation; malate dehydrogenase and carbamoyl-phosphate synthase are metabolic enzymes; and the ABC transporter is a membrane-bound protein. In addition, a hypothetical protein was identified. The role of the DNA repair gene uvrB in resistance to RNI was further confirmed by investigating the sensitivity of uvrB deletion mutant and complementation by C. burnetii uvrB. Deletion of two other components of the UvrABC nuclease, uvrA and uvrC also renders the cell sensitive to RNI. The relationship between UvrABC and nitrosative stress is discussed.