title: Structural insights into the metabolism of 2-chlorodibenzofuran by an evolved biphenyl dioxygenase.
abstract: The biphenyl dioxygenase of Burkholderia xenovorans LB400 (BphAE(LB400)) is a Rieske-type oxygenase that catalyzes the stereospecific oxygenation of many heterocyclic aromatics including dibenzofuran. In a previous work, we evolved BphAE(LB400) and obtained BphAE(RR41). This variant metabolizes dibenzofuran and 2-chlorodibenzofuran more efficiently than BphAE(LB400). However, the regiospecificity of BphAE(RR41) toward these substrates differs. Dibenzofuran is metabolized principally through a lateral dioxygenation whereas 2-chlorodibenzofuran is metabolized principally through an angular dioxygenation. In order to explain this difference, we examined the crystal structures of both substrate-bound forms of BphAE(RR41) obtained under anaerobic conditions. This structure analysis, in combination with biochemical data for a Ser283Gly mutant provided evidences that the substrate is compelled to move after oxygen-binding in BphAE(RR41):dibenzofuran. In BphAE(RR41):2-chlorodibenzofuran, the chlorine atom is close to the side chain of Ser283. This contact is missing in the BphAE(RR41):dibenzofuran, and strong enough in the BphAE(RR41):2-chlorodibenzofuran to help prevent substrate movement during the catalytic reaction.
authors.affiliation: Department of Biological Sciences and Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Pravindra
authors.initials: P
authors.lastname: Kumar
authors.forename: Mahmood
authors.initials: M
authors.lastname: Mohammadi
authors.forename: Sonali
authors.initials: S
authors.lastname: Dhindwal
authors.forename: Thi Thanh My
authors.initials: TT
authors.lastname: Pham
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Bolin
authors.forename: Michel
authors.initials: M
authors.lastname: Sylvestre
mesh_terms: D001572:Benzofurans / Q000378:metabolism*; D019117:Burkholderia / Q000201:enzymology*; D002384:Catalysis; D003460:Crystallization; D049308:Dioxygenases / Q000737:chemistry* / Q000235:genetics; D005998:Glycine / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D011487:Protein Conformation; D012694:Serine / Q000737:chemistry / Q000235:genetics
chemical_list: D001572:Benzofurans; D012694:Serine; D049308:Dioxygenases; C014402:2-chlorodibenzofuran; D005998:Glycine