title: GolS controls the response to gold by the hierarchical induction of Salmonella-specific genes that include a CBA efflux-coding operon.
abstract: Salmonella employs a specific set of proteins that allows it to detect the presence of gold salts in the environment and to mount the appropriate resistance response. This includes a P-type ATPase, GolT, and a small cytoplasmic metal binding protein, GolB. Their expression is controlled by a MerR-like sensor, GolS, which is highly selective for Au ions. Here, we identify a new GolS-controlled operon named gesABC which codes for a CBA efflux system, and establish its role in Au resistance. GesABC can also mediate drug resistance when induced by Au in a GolS-dependent manner, in a strain deleted in the main drug transporter acrAB. The GolS-controlled transcription of gesABC differs from the other GolS-regulated loci. It is activated by gold, but not induced by copper, even in a strain deleted of the main Cu transporter gene copA, which triggers a substantial GolS-dependent induction of golTS and golB. We demonstrate that the Au-dependent induction of gesABC transcription requires higher GolS levels than for the other members of the gol regulon. This correlates with a divergent GolS operator in the gesABC promoter. We propose that the hierarchical induction within the gol regulon allows Salmonella to cope with Au-contaminated environments.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Universidad Nacional de Rosario, Suipacha 531, S2002LRK-Rosario, Argentina.
authors.forename: Lucas B
authors.initials: LB
authors.lastname: Pontel
authors.forename: María E Pérez
authors.initials: ME
authors.lastname: Audero
authors.forename: Martín
authors.initials: M
authors.lastname: Espariz
authors.forename: Susana K
authors.initials: SK
authors.lastname: Checa
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Soncini
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D006046:Gold / Q000494:pharmacology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D011485:Protein Binding; D018085:Regulon / Q000235:genetics; D012475:Salmonella / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D001426:Bacterial Proteins; D006046:Gold