X-ray structure of the direct electron transfer-type FAD glucose dehydrogenase catalytic subunit complexed with a hitchhiker protein.

Hiromi Yoshida,Keiichi Yoshimatsu,Koji Sode,Tomohiko Yamazaki,Stefano Ferri,Wakako Tsugawa,Katsuhiro Kojima,Shigehiro Kamitori,Masaki Shiota

doi:10.1107/s2059798319010878

Abstract

The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe-4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit. The structure of the complex revealed that these two molecules are connected through disulfide bonds and hydrophobic interactions, and that the formation of disulfide bonds is required to stabilize the catalytic subunit. The structure of the complex revealed the putative position of the electron-transfer subunit. A comparison of the structures of BcGDHγα and membrane-bound fumarate reductases suggested that the whole BcGDH complex, which also includes the membrane-bound β-subunit containing three heme c moieties, may form a similar overall structure to fumarate reductases, thus accomplishing effective electron transfer.

Highlights

Various sugar oxidoreductases have been reported to be inherently capable of direct electron transfer to electrodes composed of carbon materials or to gold electrodes
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)
One of the representative groups of direct electron transfertype (DET-type) dehydrogenases consists of cellobiose dehydrogenases (CDHs), which are composed of a catalytic domain harboring FAD and a heme b-type electron-transfer domain

Summary

Introduction

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 electron-transfer domains or subunits, which are responsible for transferring electrons to the external electron acceptor, are categorized by the type of heme (heme b or c) that is present in the electron-transfer domain or subunit. One of the representative groups of direct electron transfertype (DET-type) dehydrogenases consists of cellobiose dehydrogenases (CDHs), which are composed of a catalytic domain harboring FAD and a heme b-type electron-transfer domain.

Methods

Results

Conclusion