Structural insights into the metabolism of 2-chlorodibenzofuran by an evolved biphenyl dioxygenase.

Pravindra Kumar (1, 2) , Mahmood Mohammadi (3) , Sonali Dhindwal (1) , Thi Thanh My Pham (3) , Jeffrey T Bolin (2) , Michel Sylvestre (3)

1 Department of Biotechnology [Roorkee)
2 Department of Biological Sciences and Center for Cancer Research
3 INRS-IAF - Institut Armand Frappier

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.

Domains: Biotechnology; Biotechnology

Pravindra Kumar, Mahmood Mohammadi, Sonali Dhindwal, Thi Thanh My Pham, Jeffrey T Bolin, et al.. Structural insights into the metabolism of 2-chlorodibenzofuran by an evolved biphenyl dioxygenase.. Biochemical and Biophysical Research Communications, 2012, 421 (4), pp.757-62. ⟨10.1016/j.bbrc.2012.04.078⟩. ⟨pasteur-00818384⟩