title: CprK crystal structures reveal mechanism for transcriptional control of halorespiration.
abstract: Halorespiration is a bacterial respiratory process in which haloorganic compounds act as terminal electron acceptors. This process is controlled at transcriptional level by CprK, a member of the ubiquitous CRP-FNR family. Here we present the crystal structures of oxidized CprK in presence of the ligand ortho-chlorophenolacetic acid and of reduced CprK in absence of this ligand. These structures reveal that highly specific binding of chlorinated, rather than the corresponding non-chlorinated, phenolic compounds in the NH(2)-terminal beta-barrels causes reorientation of these domains with respect to the central alpha-helix at the dimer interface. Unexpectedly, the COOH-terminal DNA-binding domains dimerize in the non-DNA binding state. We postulate the ligand-induced conformational change allows formation of interdomain contacts that disrupt the DNA domain dimer interface and leads to repositioning of the helix-turn-helix motifs. These structures provide a structural framework for further studies on transcriptional control by CRP-FNR homologs in general and of halorespiration regulation by CprK in particular.
authors.affiliation: Manchester Interdisciplinary Biocentre, P. O. Box 88, Manchester, M60 1QD, United Kingdom.
authors.forename: M Gordon
authors.initials: MG
authors.lastname: Joyce
authors.forename: Colin
authors.initials: C
authors.lastname: Levy
authors.forename: Krisztina
authors.initials: K
authors.lastname: Gábor
authors.forename: Stelian M
authors.initials: SM
authors.lastname: Pop
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Biehl
authors.forename: Tzanko I
authors.initials: TI
authors.lastname: Doukov
authors.forename: Jodi M
authors.initials: JM
authors.lastname: Ryter
authors.forename: Hortense
authors.initials: H
authors.lastname: Mazon
authors.forename: Hauke
authors.initials: H
authors.lastname: Smidt
authors.forename: Robert H H
authors.initials: RH
authors.lastname: van den Heuvel
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Ragsdale
authors.forename: John
authors.initials: J
authors.lastname: van der Oost
authors.forename: David
authors.initials: D
authors.lastname: Leys
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003460:Crystallization; D045858:Desulfitobacterium / Q000235:genetics* / Q000378:metabolism; D019281:Dimerization; D015964:Gene Expression Regulation, Bacterial; D010648:Phenylacetates / Q000378:metabolism; D017433:Protein Structure, Secondary; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D010648:Phenylacetates; C029718:3-chloro-4-hydroxyphenylacetic acid; C005756:2-hydroxyphenylacetic acid