Identification and characterization of a novel aminoglycoside -nucleotidyltransferase ANT(6)-If from PATH554.

Background: , a species of genus of the family , exists widely in environments and habitats in various plants and worms, and occasionally causes human infections. This work aimed to characterize the function of a novel aminoglycoside -nucleotidyltransferase resistance gene, designated , from a strain PATH554.

Methods: Molecular cloning, antimicrobial susceptibility testing, enzyme expression and purification, and kinetic analysis were used to validate the function of the novel gene. Whole-genome sequencing and comparative genomic analysis were performed to investigate the phylogenetic relationship of ANT(6)-If and other aminoglycoside -nucleotidyltransferases, and the synteny of related sequences.

Results: The recombinant with the cloned gene (pMD19-/DH5α) demonstrated a 128-fold increase of minimum inhibitory concentration level against streptomycin, compared with the control strains (DH5α and pMD19/DH5α). The kinetic parameter of ANT(6)-If for streptomycin was 9.01 × 10 M·s. Among the function-characterized resistance genes, ANT(6)-If shared the highest amino acid sequence identity of 75.35% with AadK. The gene was located within a relatively conserved genomic region in the chromosome.

Conclusion: conferred resistance to streptomycin. The study of a novel resistance gene in an unusual environmental bacterium in this work contributed to elucidating the resistance mechanisms in the microorganisms.