Molecular insights into the catalytic mechanism of plasticizer degradation by a monoalkyl phthalate hydrolase

Abstract

Phthalate acid esters (PAEs), a group of xenobiotic compounds used extensively as plasticizers, have attracted increasing concern for adverse effects to human health and the environment. Microbial degradation relying on PAE hydrolases is a promising treatment. However, only a limited number of PAE hydrolases were characterized to date. Here we report the structures of MehpH, a monoalkyl phthalate (MBP) hydrolase that catalyzes the reaction of MBP to phthalic acid and the corresponding alcohol, in apo and ligand-bound form. The structures reveal a positively-charged catalytic center, complementary to the negatively-charged carboxyl group on MBP, and a penetrating tunnel that serves as exit of alcohol. The study provides a first glimpse into the enzyme-substrate binding model for PAE hydrolases, leading strong support to the development of better enzymes in the future.

A Novel and Efficient Phthalate Hydrolase from Acinetobacter sp. LUNF3: Molecular Cloning, Characterization and Catalytic Mechanism

“…According to the results of molecular docking and enzyme assay, the interaction between MIBP and His399 affects the activity of GTW28_17760, a hydrolase from family VII capable of hydrolyzing DIBP and MIBP [ 20 ]. The catalytic mechanisms of some monoalkyl PAE hydrolases from family V are also elucidated [ 18 , 28 ]. Altogether, the catalytic mechanisms of PAE hydrolases from other families require to be further resolved.…”