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GolS controls the response to gold by the hierarchical induction of Salmonella ‐specific genes that include a CBA efflux‐coding operon

2007; Wiley; Volume: 66; Issue: 3 Linguagem: Inglês

10.1111/j.1365-2958.2007.05963.x

1365-2958

Lucas B. Pontel, María E. Pérez Audero, Martín Espariz, Susana K. Checa, Fernando C. Soncini,

Drug Transport and Resistance Mechanisms

Summary 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.