Date Published: September 01, 2019
Publisher: International Union of Crystallography
Author(s): Hiromi Yoshida, Katsuhiro Kojima, Masaki Shiota, Keiichi Yoshimatsu, Tomohiko Yamazaki, Stefano Ferri, Wakako Tsugawa, Shigehiro Kamitori, Koji Sode.
The X-ray structure of the catalytic subunit of Burkholderia cepacia FAD glucose dehydrogenase complexed with a hitchhiker protein was determined as a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. The 3Fe–4S cluster is present at the surface of the catalytic subunit and serves in the intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit.
Various sugar oxidoreductases (dehydrogenases) have been reported to be inherently capable of direct electron transfer to electrodes composed of carbon materials or to gold electrodes. These dehydrogenases harbor an electron-transfer domain or subunit, together with a catalytic domain or subunit. The catalytic domains or subunits, which are responsible for catalyzing sugar oxidation, are categorized by their cofactor: flavin adenine dinucleotide (FAD) or pyrroloquinoline quinone (PQQ). The electron-transfer domains or subunits, which are responsible for transferring electrons to the external electron acceptor, are also categorized by the type of heme (heme b or c) that is present in the electron-transfer domain or subunit.
A DALI search (Holm & Rosenström, 2010 ▸; Holm & Laakso, 2016 ▸) revealed many proteins that are structurally similar to the α-subunit of BcGDHγα, with high Z-scores in the range 23.4–33.0 (Supplementary Table S1). These enzymes are categorized as members of the FAD-containing glucose-methanol-choline oxidoreductase (GMC) family.
The following references relate to PDB entries that are mentioned in the supporting information to this article: Batra et al. (2016 ▸), Djordjevic & Stock (1997 ▸, 1998 ▸), Golden et al. (2014 ▸), Leys et al. (1999 ▸), Liu et al. (2015 ▸), Mugo et al. (2013 ▸), Pitsawong et al. (2010 ▸), Salvi et al. (2014 ▸), Tan et al. (2015 ▸), Wohlfahrt et al. (1999 ▸), Yoshida et al. (2015 ▸) and Zhang et al. (2014 ▸).