ChpR is a chlorpyrifos-responsive transcription regulator in Sinorhizobium meliloti

Abstract

The broad-spectrum organophosphate insecticide chlorpyrifos (CPF)-inducible locus, chpAB, was identified on the endogenous plasmid pSymB in Sinorhizobium meliloti. The S. meliloti chpA promoter was highly induced by CPF and was induced at much lower levels by diazinon and ethion. Transcription of chpA was dependent on chpR, a CadC family transcriptional regulator located upstream of, and divergently transcribed from, chpAB. ChpR was able to mediate the CPF-inducible expression of the S. melilotichpA promoter in Escherichia coli through direct interaction with the chpAB promoter. The chpR-chpA intergenic regions of several bacterial chpRAB operons were aligned and a putative ChpR-binding sequence was proposed. Both the ChpR transcription factor and chpA promoter constitute a good candidate system for genetic-based biosensor development. © 2010 S. Karger AG, Basel.