title: Triclosan Resistance in a Bacterial Fish Pathogen, Aeromonas salmonicida subsp. salmonicida, is Mediated by an Enoyl Reductase, FabV.
abstract: Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX(8)K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.
authors.affiliation: Department of Applied Biology, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Raees
authors.initials: R
authors.lastname: Khan
authors.affiliation: Department of Applied Biology, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Myung Hwan
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Department of Applied Biology, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Hae-Jin
authors.initials: HJ
authors.lastname: Joo
authors.affiliation: Department of Applied Bioscience, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Yong-Hoon
authors.initials: YH
authors.lastname: Jung
authors.affiliation: Department of Applied Biology, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Shabir
authors.initials: S
authors.lastname: Ahmad
authors.affiliation: Department of Applied Bioscience, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Department of Applied Biology, Dong-A University, Busan 604-714, Republic of Korea.|Department of Applied Bioscience, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Seon-Woo
authors.initials: SW
authors.lastname: Lee
mesh_terms: D048409:Aeromonas salmonicida / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial / Q000235:genetics; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005399:Fishes / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D054730:Protein Interaction Domains and Motifs; D016415:Sequence Alignment; D014158:Transcription, Genetic; D014260:Triclosan / Q000494:pharmacology*
chemical_list: D000891:Anti-Infective Agents, Local; D014260:Triclosan; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific)