Phylogenetic analysis of chromosomally determined qnr and related proteins

Abstract

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.

Fig 1

Phylogenetic tree of Qnr from gammaproteobacteria. The tree was constructed using the maximum-likelihood method in MEGA5 (35) based on the JTT model (36) with 1,000 bootstrap replicates. The percentages of replicate trees in which the associated taxa clustered together in the bootstrap test are shown next to the branches (37). The tree is drawn to scale, with branch lengths measured in number of substitutions per site. Plasmid-mediated qnr genes and those from Table 1 used to search for homology are shown in bold.

Fig 2

Phylogenetic tree of Qnr from Gram-positive bacteria, derived as described for Fig. 1. Qnr from the organisms shown in bold was used to initiate the search.

Fig 3

Phylogenetic tree of matches to MfpA, derived as described for Fig. 1. MfpA from the organisms shown in bold was used to initiate the search.