Open AccessCharacterization of a Novel PQQ-Dependent Quinohemoprotein Pyranose Dehydrogenase from Coprinopsis cinerea Classified into Auxiliary Activities Family 12 in Carbohydrate-Active Enzymes
Author(s) -
Kouta Takeda,
Hirotoshi Matsumura,
Takuya Ishida,
Masahiro Samejima,
Hiroyuki Ohno,
Makoto Yoshida,
Kiyohiko Igarashi,
Nobuhumi Nakamura
Publication year - 2015
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0115722
Subject(s) - heme , pyranose , cellobiose dehydrogenase , chemistry , dehydrogenase , stereochemistry , pyrroloquinoline quinone , cofactor , biochemistry , enzyme kinetics , cytochrome c , active site , enzyme , cellobiose , cellulase , mitochondrion
The basidiomycete Coprinopsis cinerea contains a quinohemoprotein ( Cc PDH named as Cc SDH 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 Cc PDH. 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 Cc PDH possesses similar biophysical properties to that in CDH. A comparison of the conformations of monosaccharides as substrates and the associated catalytic efficiency ( k cat / K m ) 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 1 C 4 chair conformation. Furthermore, a binding study shows a high binding affinity of Cc PDH for cellulose, suggesting that Cc PDH function is related to the enzymatic degradation of plant cell wall.