AUTHOR=Arruda Letícia M. , Monteiro Lummy M. O. , Silva-Rocha Rafael 

TITLE=The Chromobacterium violaceum ArsR Arsenite Repressor Exerts Tighter Control on Its Cognate Promoter Than the Escherichia coli System

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01851

DOI=10.3389/fmicb.2016.01851

ISSN=1664-302X

ABSTRACT=<p>Environmental bacteria are endowed with several regulatory systems that have potential applications in biotechnology. In this report, we characterize the arsenic biosensing features of the <italic>ars</italic> response system from <italic>Chromobacterium violaceum</italic> in the heterologous host <italic>Escherichia coli</italic>. We show that the native <italic>Pars/arsR</italic> system of <italic>C. violaceum</italic> outperforms the chromosomal <italic>ars</italic> copy of <italic>E. coli</italic> when 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. <italic>In vivo</italic> titration experiments indicate that ArsR from <italic>C. violaceum</italic> has stronger binding affinity for its target promoter than the regulator from <italic>E. coli</italic> does. Additionally, arsenite induction experiments at saturating regulator concentration demonstrates that although the <italic>Pars/arsR</italic> system from <italic>E. coli</italic> displays a gradual response to increasing concentration of the inducer, the system from <italic>C. violaceum</italic> has 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.</p>