PDBsum entry 6gsb

Oxidoreductase

PDB id: 6gsb

Contents

Protein chains

206 a.a.

Metals

_MN ×2

Waters ×626

PDB id:

6gsb

Name:

Oxidoreductase

Title:

Sphingobacterium sp. T2 manganese superoxide dismutase catalyses the oxidative demethylation of polymeric lignin via generation of hydroxyl radical

Structure:

Superoxide dismutase. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Sphingobacterium spiritivorum. Organism_taxid: 258. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.45Å R-factor: 0.150 R-free: 0.169

Authors:

G.M.Rashid,X.Zhang,R.C.Wilkinson,V.Fulop,B.Cottyn,S.Baumberger, D.H.Bugg

Key ref:

G.M.M.Rashid et al. (2018). Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical. ACS Chem Biol, 13, 2920-2929. PubMed id: 30247873 DOI: 10.1021/acschembio.8b00557

Date:

13-Jun-18 Release date: 03-Oct-18

Protein chains

A0A0M3KL50  (A0A0M3KL50_SPHSI) -  Superoxide dismutase from Sphingobacterium spiritivorum

Seq: 181 a.a.

Struc: 206 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.15.1.1 - superoxide dismutase.
• Reaction: 2 superoxide + 2 H⁺ = H2O2 + O2
• Cofactor: Fe cation or Mn(2+) or (Zn(2+) and Cu cation)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1021/acschembio.8b00557

ACS Chem Biol 13:2920-2929 (2018)

PubMed id: 30247873

Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical.

G.M.M.Rashid, X.Zhang, R.C.Wilkinson, V.Fülöp, B.Cottyn, S.Baumberger, T.D.H.Bugg.

ABSTRACT

Sphingobacterium sp. T2 contains two extracellular manganese superoxide dismutase enzymes which exhibit unprecedented activity for lignin oxidation but via an unknown mechanism. Enzymatic treatment of lignin model compounds gave products whose structures were indicative of aryl-Cα oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. ¹⁸O labeling studies on the SpMnSOD-catalyzed oxidation of lignin model compound guiaiacylglycerol-β-guaiacyl ether indicated that the an oxygen atom inserted by the enzyme is derived from superoxide or peroxide. Analysis of an alkali lignin treated by SpMnSOD1 by quantitative ³¹P NMR spectroscopy demonstrated 20-40% increases in phenolic and aliphatic OH content, consistent with lignin demethylation and some internal oxidative cleavage reactions. Assay for hydroxyl radical generation using a fluorometric hydroxyphenylfluorescein assay revealed the release of 4.1 molar equivalents of hydroxyl radical by SpMnSOD1. Four amino acid replacements in SpMnSOD1 were investigated, and A31H or Y27H site-directed mutant enzymes were found to show no lignin demethylation activity according to ³¹P NMR analysis. Structure determination of the A31H and Y27H mutant enzymes reveals the repositioning of an N-terminal protein loop, leading to widening of a solvent channel at the dimer interface, which would provide increased solvent access to the Mn center for hydroxyl radical generation.