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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Structural and functional characterisation of multi-copper oxidase CueO from lignin-degrading bacterium Ochrobactrum sp reveal its activity towards lignin model compounds and lignosulfonate

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Author(s):
Granja-Travez, Rommel Santiago [1] ; Wilkinson, Rachael C. [2] ; Persinoti, Gabriela Felix [3] ; Squina, Fabio M. [4] ; Fulop, Vilmos [2] ; Bugg, Timothy D. H. [1]
Total Authors: 6
Affiliation:
[1] Univ Warwick, Dept Chem, Coventry CV4 7AL, W Midlands - England
[2] Univ Warwick, Sch Life Sci, Coventry, W Midlands - England
[3] CNPEM, Lab Nacl Ciencia & Tecnol Bioetanol CTBE, Campinas, SP - Brazil
[4] Univ Sorocaba, Programa Proc Tecnol & Ambientais, Sorocaba - Brazil
Total Affiliations: 4
Document type: Journal article
Source: FEBS Journal; v. 285, n. 9, p. 1684-1700, MAY 2018.
Web of Science Citations: 8
Abstract

The identification of enzymes responsible for oxidation of lignin in lignin-degrading bacteria is of interest for biotechnological valorization of lignin to renewable chemical products. The genome sequences of two lignin-degrading bacteria, Ochrobactrum sp., and Paenibacillus sp., contain no B-type DyP peroxidases implicated in lignin degradation in other bacteria, but contain putative multicopper oxidase genes. Multi-copper oxidase CueO from Ochrobactrum sp. was expressed and reconstituted as a recombinant laccase-like enzyme, and kinetically characterized. Ochrobactrum CueO shows activity for oxidation of -aryl ether and biphenyl lignin dimer model compounds, generating oxidized dimeric products, and shows activity for oxidation of Ca-lignosulfonate, generating vanillic acid as a low molecular weight product. The crystal structure of Ochrobactrum CueO (OcCueO) has been determined at 1.1 angstrom resolution (PDB: ), showing a four-coordinate mononuclear type I copper center with ligands His495, His434 and Cys490 with Met500 as an axial ligand, similar to that of Escherichiacoli CueO and bacterial azurin proteins, whereas fungal laccase enzymes contain a three-coordinate type I copper metal center. A trinuclear type 2/3 copper cluster was modeled into the active site, showing similar structure to E.coli CueO and fungal laccases, and three solvent channels leading to the active site. Site-directed mutagenesis was carried out on amino acid residues found in the solvent channels, indicating the importance for residues Asp102, Gly103, Arg221, Arg223, and Asp462 for catalytic activity. The work identifies a new bacterial multicopper enzyme with activity for lignin oxidation, and implicates a role for bacterial laccase-like multicopper oxidases in some lignin-degrading bacteria. DatabaseStructural data are available in the PDB under the accession number . (AU)

FAPESP's process: 15/50590-4 - Lignin valorization in cellulosic ethanol plants: biocatalytic conversion via ferulic acid to high value chemicals
Grantee:Fábio Márcio Squina
Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants