Structural Basis of the Enhanced Pollutant-Degrading Capabilities of an Engineered Biphenyl Dioxygenase

Dhindwal, Sonali; Gomez-Gil, Leticia; Neau, David; Pham, Thi Thanh My; Sylvestre, Michel; Eltis, Lindsay; Bolin, Jeffrey et Kumar, Pravindra (2016). Structural Basis of the Enhanced Pollutant-Degrading Capabilities of an Engineered Biphenyl Dioxygenase Journal of Bacteriology , vol. 198 , nº 10. pp. 1499-1512. DOI: 10.1128/jb.00952-15.

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Résumé

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en PDF. Biphenyl dioxygenase, the first enzyme of the biphenyl catabolic pathway, is a major determinant of which polychlorinated biphenyl (PCB) congeners are metabolized by a given bacterial strain. Ongoing efforts aim to engineer BphAE, the oxygenase component of the enzyme, to efficiently transform a wider range of congeners. BphAEII9, a variant of BphAELB400 in which a seven-residue segment, 335TFNNIRI341, has been replaced by the corresponding segment of BphAEB356, 333GINTIRT339, transforms a broader range of PCB congeners than does either BphAELB400 or BphAEB356, including 2,6-dichlorobiphenyl, 3,3′-dichlorobiphenyl, 4,4′-dichlorobiphenyl, and 2,3,4′-trichlorobiphenyl. To understand the structural basis of the enhanced activity of BphAEII9, we have determined the three-dimensional structure of this variant in substrate-free and biphenyl-bound forms. Structural comparison with BphAELB400 reveals a flexible active-site mouth and a relaxed substrate binding pocket in BphAEII9 that allow it to bind different congeners and which could be responsible for the enzyme's altered specificity. Biochemical experiments revealed that BphAEII9 transformed 2,3,4′-trichlorobiphenyl and 2,2′,5,5′-tetrachlorobiphenyl more efficiently than did BphAELB400 and BphAEB356. BphAEII9 also transformed the insecticide dichlorodiphenyltrichloroethane (DDT) more efficiently than did either parental enzyme (apparent kcat/Km of 2.2 ± 0.5 mM−1 s−1, versus 0.9 ± 0.5 mM−1 s−1 for BphAEB356). Studies of docking of the enzymes with these three substrates provide insight into the structural basis of the different substrate selectivities and regiospecificities of the enzymes.

Type de document:	Article
Mots-clés libres:	-
Centre:	Centre INRS-Institut Armand Frappier
Date de dépôt:	24 août 2016 13:50
Dernière modification:	08 juin 2023 18:32
URI:	https://espace.inrs.ca/id/eprint/4514

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