Hybrid proteins for the screening of transcription regulators of reductive dehalogenase gene clusters

In the past decade, research on the transcription regulation of reductive dehalogenase (rdh) gene clusters (for a recent review, see [1]) revealed a new set of CRP/FNR-type transcription regulators, called RdhK [2,3]. Several members of this family have been characterized in Desulfitobacterium hafniense. CprK1 (also known as RdhK6 [3]) is responsible for the regulation of the chlorophenol rdh operon [4-5]. The binding of the CprK1 N-terminal domain to 3-chloro-4-hydroxyphenylacetate (effector) promotes C-terminal specific interaction with a DNA target (dehalobox) in the operon promoter which leads to transcription. The presence of 25 copies of rdhK genes in Dehalobacter restrictus suggests an important regulation network of organohalide respiration. Moreover, the proximity of rdhK genes in rdh gene clusters [6] offers an indirect way to identify the substrate of yet uncharacterized RdhA enzymes.