title: Divergent roles of CprK paralogues from Desulfitobacterium hafniense in activating gene expression.
abstract: Gene duplication and horizontal gene transfer play an important role in the evolution of prokaryotic genomes. We have investigated the role of three CprK paralogues from the cAMP receptor protein-fumarate and nitrate reduction regulator (CRP-FNR) family of transcriptional regulators that are encoded in the genome of Desulfitobacterium hafniense DCB-2 and possibly regulate expression of genes involved in the energy-conserving terminal reduction of organohalides (halorespiration). The results from in vivo and in vitro promoter probe assays show that two regulators (CprK1 and CprK2) have an at least partially overlapping effector specificity, with preference for ortho-chlorophenols, while meta-chlorophenols proved to be effectors for CprK4. The presence of a potential transposase-encoding gene in the vicinity of the cprK genes indicates that their redundancy is probably caused by mobile genetic elements. The CprK paralogues activated transcription from promoters containing a 14 bp inverted repeat (dehalobox) that closely resembles the FNR-box. We found a strong negative correlation between the rate of transcriptional activation and the number of nucleotide changes from the optimal dehalobox sequence (TTAAT-N4-ATTAA). Transcription was initiated by CprK4 from a promoter that is situated upstream of a gene encoding a methyl-accepting chemotaxis protein. This might be the first indication of taxis of an anaerobic bacterium to halogenated aromatic compounds.
authors.affiliation: Wageningen University and Research Centre, Laboratory of Microbiology, Dreijenplein 10, Wageningen 6703-HB, The Netherlands.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Gábor
authors.affiliation: Wageningen University and Research Centre, Laboratory of Microbiology, Dreijenplein 10, Wageningen 6703-HB, The Netherlands.
authors.forename: Kagnew
authors.initials: K
authors.lastname: Hailesellasse Sene
authors.affiliation: Wageningen University and Research Centre, Laboratory of Microbiology, Dreijenplein 10, Wageningen 6703-HB, The Netherlands.
authors.forename: Hauke
authors.initials: H
authors.lastname: Smidt
authors.affiliation: Wageningen University and Research Centre, Laboratory of Microbiology, Dreijenplein 10, Wageningen 6703-HB, The Netherlands.
authors.forename: Willem M
authors.initials: WM
authors.lastname: de Vos
authors.affiliation: Wageningen University and Research Centre, Laboratory of Microbiology, Dreijenplein 10, Wageningen 6703-HB, The Netherlands.
authors.forename: John
authors.initials: J
authors.lastname: van der Oost
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D045858:Desulfitobacterium / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D014157:Transcription Factors