Characterization of a novel PQQ-dependent quinohemoprotein pyranose dehydrogenase from Coprinopsis cinerea classified into auxiliary activities family 12 in carbohydrate-active enzymes

PLoS One. 2015 Feb 13;10(2):e0115722. doi: 10.1371/journal.pone.0115722. eCollection 2015.

Abstract

The basidiomycete Coprinopsis cinerea contains a quinohemoprotein (CcPDH named as CcSDH in our previous paper), which is a new type of pyrroloquinoline-quinone (PQQ)-dependent pyranose dehydrogenase and is the first found among all eukaryotes. This enzyme has a three-domain structure consisting of an N-terminal heme b containing a cytochrome domain that is homologous to the cytochrome domain of cellobiose dehydrogenase (CDH; EC 1.1.99.18) from the wood-rotting basidiomycete Phanerochaete chrysosporium, a C-terminal family 1-type carbohydrate-binding module, and a novel central catalytic domain containing PQQ as a cofactor. Here, we describe the biochemical and electrochemical characterization of recombinant CcPDH. UV-vis and resonance Raman spectroscopic studies clearly reveal characteristics of a 6-coordinated low-spin heme b in both the ferric and ferrous states, as well as intramolecular electron transfer from the PQQ to heme b. Moreover, the formal potential of the heme was evaluated to be 130 mV vs. NHE by cyclic voltammetry. These results indicate that the cytochrome domain of CcPDH possesses similar biophysical properties to that in CDH. A comparison of the conformations of monosaccharides as substrates and the associated catalytic efficiency (kcat/Km) of CcPDH indicates that the enzyme prefers monosaccharides with equatorial C-2, C-3 hydroxyl groups and an axial C-4 hydroxyl group in the 1C4 chair conformation. Furthermore, a binding study shows a high binding affinity of CcPDH for cellulose, suggesting that CcPDH function is related to the enzymatic degradation of plant cell wall.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agaricales / enzymology*
  • Amino Acid Sequence
  • Animals
  • Biocatalysis
  • Carbohydrate Metabolism*
  • Electrochemistry
  • Molecular Sequence Data
  • Oxidoreductases / chemistry*
  • Oxidoreductases / metabolism*
  • PQQ Cofactor / metabolism*
  • Protein Structure, Tertiary

Substances

  • PQQ Cofactor
  • Oxidoreductases

Grants and funding

This work was supported financially by a Grant-in-Aid for Scientific Research (No. 21605004 to N.N.) from the Japan Society for the Promotion of Science (JSPS), by a Grant-in-Aid for Innovative Areas (No. 24114001 and 24114008 to K.I.) from the Japanese Ministry of Education, Culture, Sports, and Technology (MEXT), and by a Grant-in-Aid for JSPS Fellows (Grant No. 268641 to K.T.). H.M. was supported by a Grant-in-Aid for JSPS Fellows (Grant No. 208304) during his postdoc period at the University of Tokyo. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.