title: Structural insights into enzymatic degradation of oxidized polyvinyl alcohol.
abstract: The ever-increasing production and use of polyvinyl alcohol (PVA) threaten our environment. Yet PVA can be assimilated by microbes in two steps: oxidation and cleavage. Here we report novel α/β-hydrolase structures of oxidized PVA hydrolase (OPH) from two known PVA-degrading organisms, Sphingopyxis sp. 113P3 and Pseudomonas sp. VM15C, including complexes with substrate analogues, acetylacetone and caprylate. The active site is covered by a lid-like β-ribbon. Unlike other esterase and amidase, OPH is unique in cleaving the CC bond of β-diketone, although it has a catalytic triad similar to that of most α/β-hydrolases. Analysis of the crystal structures suggests a double-oxyanion-hole mechanism, previously only found in thiolase cleaving β-ketoacyl-CoA. Three mutations in the lid region showed enhanced activity, with potential in industrial applications.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Lihu Ave. 1800, Wuxi 214122 (China).
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.forename: Long
authors.initials: L
authors.lastname: Liu
authors.forename: Jianghua
authors.initials: J
authors.lastname: Li
authors.forename: Chun-Hsiang
authors.initials: CH
authors.lastname: Huang
authors.forename: Hsiu-Chien
authors.initials: HC
authors.lastname: Chan
authors.forename: Feifei
authors.initials: F
authors.lastname: Ren
authors.forename: Dongxu
authors.initials: D
authors.lastname: Jia
authors.forename: Andrew H-J
authors.initials: AH
authors.lastname: Wang
authors.forename: Rey-Ting
authors.initials: RT
authors.lastname: Guo
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D055162:Biocatalysis; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D020134:Catalytic Domain; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology; D008958:Models, Molecular; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D011549:Pseudomonas / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D011142:Polyvinyl Alcohol; D002265:Carboxylic Ester Hydrolases; C409492:oxidized polyvinyl alcohol hydrolase, Pseudomonas sp.
keywords: beta-diketone hydrolases; catalytic triad; double oxyanion holes; environmental chemistry; hydrolases; microbial assimilation