laboratory of microbiology, wageningen university and research centre, hesselink van suchtelenweg 4, 6703 ct wageningen, the netherlands
the recently identified cprk branch of the crp (cyclic amp receptor protein)-fnr (fumarate and nitrate reduction regulator) family of transcriptional regulators includes proteins that activate the transcription of genes encoding proteins involved in reductive dehalogenation of chlorinated aromatic compounds. here we report the characterization of the cprk1 protein from desulfitobacterium hafniense, an anaerobic low-g+c gram-positive bacterium that is capable of reductive dechlorination of 3-chloro-4-hydroxyphenylacetic acid (cl-ohpa). the gene encoding cprk1 was cloned and functionally overexpressed in escherichia coli, and the protein was subsequently purified to homogeneity. to investigate the interaction of cprk1 with three of its predicted binding sequences (dehaloboxes), we performed in vitro dna-binding assays (electrophoretic mobility shift assays) as well as in vivo promoter probe assays. our result......