Identification of manganese superoxide dismutase from Sphingobacterium sp. T2 as a novel bacterial enzyme for lignin oxidation

DOI: 10.1021/acschembio.5b00298
PMID: 26198187

Authors: Goran M. M. Rashid (University of Warwick) , Charles R. Taylor (University of Warwick) , Yangqingxue Liu (University of Warwick) , Xiaoyang Zhang (University of Warwick) , Dean Rea (University of Warwick) , Vilmos Fülöp (University of Warwick) , Timothy D. H. Bugg (University of Warwick)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Chemical Biology , VOL 10 (10)

State: Published (Approved)
Published: July 2015
Diamond Proposal Number(s): 8359

Abstract: The valorization of aromatic heteropolymer lignin is an important unsolved problem in the development of a biomass-based biorefinery, for which novel high-activity biocatalysts are needed. Sequencing of the genomic DNA of lignin-degrading bacterial strain Sphingobacterium sp. T2 revealed no matches to known lignin-degrading genes. Proteomic matches for two manganese superoxide dismutase proteins were found in partially purified extracellular fractions. Recombinant MnSOD1 and MnSOD2 were both found to show high activity for oxidation of Organosolv and Kraft lignin, and lignin model compounds, generating multiple oxidation products. Structure determination revealed that the products result from aryl–Cα and Cα–Cβ bond oxidative cleavage and O-demethylation. The crystal structure of MnSOD1 was determined to 1.35 Å resolution, revealing a typical MnSOD homodimer harboring a five-coordinate trigonal bipyramidal Mn(II) center ligated by three His, one Asp, and a water/hydroxide in each active site. We propose that the lignin oxidation reactivity of these enzymes is due to the production of a hydroxyl radical, a highly reactive oxidant. This is the first demonstration that MnSOD is a microbial lignin-oxidizing enzyme.

Journal Keywords: Lignin Valorisation; Lignin Oxidation; Manganese Superoxide Dismutase; Sphingobacterium

Diamond Keywords: Bacteria; Enzymes; Biofuel

Subject Areas: Biology and Bio-materials, Chemistry, Energy


Instruments: I03-Macromolecular Crystallography

Added On: 25/09/2015 14:44

Discipline Tags:

Bioenergy Sustainable Energy Systems Energy Biochemistry Catalysis Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)