title: Characterization of Dye-decolorizing Peroxidase (DyP) from Thermomonospora curvata Reveals Unique Catalytic Properties of A-type DyPs.
abstract: Dye-decolorizing peroxidases (DyPs) comprise a new family of heme peroxidases, which has received much attention due to their potential applications in lignin degradation. A new DyP from Thermomonospora curvata (TcDyP) was identified and characterized. Unlike other A-type enzymes, TcDyP is highly active toward a wide range of substrates including model lignin compounds, in which the catalytic efficiency with ABTS (kcat(app)/Km(app) = (1.7 × 10(7)) m(-1) s(-1)) is close to that of fungal DyPs. Stopped-flow spectroscopy was employed to elucidate the transient intermediates as well as the catalytic cycle involving wild-type (wt) and mutant TcDyPs. Although residues Asp(220) and Arg(327) are found necessary for compound I formation, His(312) is proposed to play roles in compound II reduction. Transient kinetics of hydroquinone (HQ) oxidation by wt-TcDyP showed that conversion of the compound II to resting state is a rate-limiting step, which will explain the contradictory observation made with the aspartate mutants of A-type DyPs. Moreover, replacement of His(312) and Arg(327) has significant effects on the oligomerization and redox potential (E°') of the enzyme. Both mutants were found to promote the formation of dimeric state and to shift E°' to a more negative potential. Not only do these results reveal the unique catalytic property of the A-type DyPs, but they will also facilitate the development of these enzymes as lignin degraders.
authors.affiliation: From the Departments of Chemistry.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: From the Departments of Chemistry.
authors.forename: Ruben
authors.initials: R
authors.lastname: Shrestha
authors.affiliation: From the Departments of Chemistry.
authors.forename: Kaimin
authors.initials: K
authors.lastname: Jia
authors.affiliation: the Protein Production Group, University of Kansas, Lawrence, Kansas 66045.
authors.forename: Philip F
authors.initials: PF
authors.lastname: Gao
authors.affiliation: Biochemistry and Molecular Biophysics, and.
authors.forename: Brian V
authors.initials: BV
authors.lastname: Geisbrecht
authors.affiliation: From the Departments of Chemistry.
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Bossmann
authors.affiliation: Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506 and.
authors.forename: Jishu
authors.initials: J
authors.lastname: Shi
authors.affiliation: From the Departments of Chemistry, pli@ksu.edu.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
mesh_terms: D039903:Actinobacteria / Q000201:enzymology*; D001426:Bacterial Proteins; D002384:Catalysis; D007700:Kinetics; D008031:Lignin / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry*; D055503:Protein Multimerization
chemical_list: D001426:Bacterial Proteins; D008031:Lignin; D009195:Peroxidase
keywords: dye-decolorizing peroxidase; enzyme kinetics; heme; lignin degradation; oligomerization; oxidation-reduction (redox); stopped-flow spectroscopy