INVESTIGADORES
CHECA Susana Karina
congresos y reuniones científicas
Título:
COMPLEX REGULATION OF THE Salmonella-SPECIFIC CBA EFFLUX PUMP gesABC
Autor/es:
DAVID, ALDANA; CERMINATI, SEBASTIÁN; CHECA, SUSANA K.; SONCINI, FERNANDO C.
Lugar:
Rosario, Santa Fe
Reunión:
Congreso; IX Congreso de Microbiología General; 2013
Institución organizadora:
Sociedad Argentina de Microbiología General (SAMIGE)
Resumen:
Salmonella
employs a specific set of proteins that allows
the detection of gold in the environment and to mount the proper response to
this injury. This includes a P-type ATPase, GolT, a small cytoplasmic metal
binding protein, GolB and a CBA efflux system GesABC. Their genes are
transcriptionally induced in the presence of gold ions by the Au-sensor GolS.
We have previously characterized the GolS-dependent operator at the promoter of
gesABC and
detected differences with the other GolS-controlled genes that results in its
delayed expression in the presence of Au ions. Besides its essential role in Au-resistance,
the GesABC system can also mediate the resistance of xenobiotics in a strain
deleted in the main drug transporter AcrAB, suggesting additional
detoxification roles. Using bioinformatics we were able to identified putative
regulatory sequences at the gesABC
promoter, as well as post-transcriptional
regulatory sequences at its 5´-untraslated region. Effective regulation of
GesABC expression was verified by the analysis of reporter constructions in
strains deleted of different stress-regulatory systems and by phenotypic
characterization of these strains. Specific regulators interactions were
verified by mapping of the binding sequence either by electrophoresis mobility
shift assays or by footprinting assays and corroborated by site-directed
mutagenesis, confirming the tight expression control exerted on this Salmonella-specific
detoxification system by different stress-induced regulators. The results
obtained here indicate that different regulatory strategies contribute to
fine-tuning the expression of GesABC in order to guarantee the proper supply of
this efflux pump under different stress conditions.