Structure Report for: 6KXH

Zhang, L., Yingli, Z., Bidhan, C.D., Zhang, C.

Title: Mutation of an atypical oxirane oxyanion hole improves regioselectivity of the alpha/beta-fold epoxide hydrolase Alp1U
Zhang L, De BC, Zhang W, Mandi A, Fang Z, Yang C, Zhu Y, Kurtan T, Zhang C
Ref: Journal of Biological Chemistry, 295:16987, 2020 : PubMed
Abstract


ESTHER: Zhang_2020_J.Biol.Chem_295_16987
PubMedSearch: Zhang 2020 J.Biol.Chem 295 16987
PubMedID: 33004437
Gene_locus related to this paper: stram-q1rqu8

Abstract

Epoxide hydrolases (EHs) have been characterized and engineered as biocatalysts that convert epoxides to valuable chiral vicinal diol precursors of drugs and bioactive compounds. Nonetheless, the regioselectivity control of the epoxide ring opening by EHs remains challenging. Alp1U is an alpha/beta-fold EH that exhibits poor regioselectivity in the epoxide hydrolysis of fluostatin C (1), and produces a pair of stereoisomers. Herein, we established the absolute configuration of the two stereoisomeric products and determined the crystal structure of Alp1U. A W186/W187/Y247 oxirane oxygen hole was identified in Alp1U that replaced the canonical Tyr/Tyr pair in alpha/beta-EHs. Mutation of residues in the atypical oxirane oxygen hole of Alp1U improved the regioselectivity for epoxide hydrolysis on 1. The single site Y247F mutation led to highly regioselective (98%) attack at C-3 of 1, while the double mutation W187F/Y247F resulted in regioselective (94%) nucleophilic attack at C-2. Furthermore, single crystal X-ray structures of the two regioselective Alp1U variants in complex with 1 were determined. These findings allowed insights into the reaction details of Alp1U, and provided a new approach for engineering regioselective epoxide hydrolases.