Phylogenetic analysis of chromosomally determined qnr and related proteins.

qnr genes were discovered on plasmids by their ability to reduce quinolone susceptibility, but homologs can be found in the genomes of at least 92 Gram-negative, Gram-positive, and strictly anaerobic bacterial species. The related pentapeptide repeat protein-encoding mfpA gene is present in the genome of at least 19 species of Mycobacterium and 10 other Actinobacteria species. The native function of these genes is not yet known.