The catalytic pocket of the ring-hydroxylating dioxygenase from Sphingomonas CHY-1

Jean Jakoncic (1, 2) , Yves Jouanneau (1, 3) , Christine Meyer (1, 3) , V. Stojanoff (4)

1 BBSI - Biochimie et biophysique des systèmes intégrés
2 BNL NSLS - Brookhaven National Laboratory Mational Synchrotron Light Source
3 LCBM - UMR 5249 - Laboratoire de Chimie et Biologie des Métaux
4 BNL - Brookhaven National Laboratory [Upton, NY]

Ring-hydroxylating dioxygenases are multicomponent bacterial enzymes that catalyze the first step in the oxidative degradation of aromatic hydrocarbons. The dioxygenase from Sphingomonas CHY-1 is unique in that it can oxidize a wide range of polycyclic aromatic hydrocarbons (PAHs). The crystal structure of its catalytic component has been determined to 1.85 Å. The catalytic domain features a large hydrophobic cavity that was occupied in part by an external ligand, possibly an indole molecule. This substrate binding cavity appeared to be much greater than that of seven other dioxygenases so far characterized. Molecular modeling studies indicated that the catalytic cavity is large enough to accommodate the five-ring benzo[a]pyrene molecule. The predicted positions of this and other PAHs in the substrate binding pocket are consistent with the product regio- and stereo-selectivity of the enzyme.

Mots clés: Dioxygenase; X ray structure; substrate binding site; PAH

Domaines: Biophysique

Jean Jakoncic, Yves Jouanneau, Christine Meyer, V. Stojanoff. The catalytic pocket of the ring-hydroxylating dioxygenase from Sphingomonas CHY-1. Biochemical and Biophysical Research Communications, 2007, 352, pp.862-866. ⟨hal-00377528⟩