title: TheChromobacterium violaceumArsR Arsenite Repressor Exerts Tighter Control on Its Cognate Promoter Than theEscherichia coliSystem.
abstract: Environmental bacteria are endowed with several regulatory systems that have potential applications in biotechnology. In this report, we characterize the arsenic biosensing features of thearsresponse system fromChromobacterium violaceumin the heterologous hostEscherichia coli. We show that the nativePars/arsRsystem ofC. violaceumoutperforms the chromosomalarscopy ofE. coliwhen exposed to micromolar concentrations of arsenite. To understand the molecular basis of this phenomenon, we analyzed the interaction between ArsR regulators and their promoter target sites as well as induction of the system at saturating concentrations of the regulators.In vivotitration experiments indicate that ArsR fromC. violaceumhas stronger binding affinity for its target promoter than the regulator fromE. colidoes. Additionally, arsenite induction experiments at saturating regulator concentration demonstrates that although thePars/arsRsystem fromE. colidisplays a gradual response to increasing concentration of the inducer, the system fromC. violaceumhas a steeper response with a stronger promoter induction after a given arsenite threshold. Taken together, these data demonstrate the characterization of a novel arsenic response element from an environmental bacterium with potentially enhanced performance that could be further explored for the construction of an arsenic biosensor.
authors.affiliation: Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil.
authors.forename: Letícia M
authors.initials: LM
authors.lastname: Arruda
authors.affiliation: Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil.
authors.forename: Lummy M O
authors.initials: LM
authors.lastname: Monteiro
authors.affiliation: Systems and Synthetic Biology Lab, Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo Ribeirão Preto, Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Silva-Rocha
keywords: ArsR/SmtB family; ars operon; arsenic response system; cis-regulatory elements; regulatory network