Ministry of Education, Culture, Sports, Science and Technology (Japan)
JP25102001
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
JP25102008
日本
Japan Science and Technology Agency
JPMJPR13L5
日本
引用
ジャーナル: Sci Rep / 年: 2017 タイトル: Visualisation of a flexible modular structure of the ER folding-sensor enzyme UGGT. 著者: Tadashi Satoh / Chihong Song / Tong Zhu / Takayasu Toshimori / Kazuyoshi Murata / Yugo Hayashi / Hironari Kamikubo / Takayuki Uchihashi / Koichi Kato / 要旨: In the endoplasmic reticulum (ER), a protein quality control system facilitates the efficient folding of newly synthesised proteins. In this system, a series of N-linked glycan intermediates ...In the endoplasmic reticulum (ER), a protein quality control system facilitates the efficient folding of newly synthesised proteins. In this system, a series of N-linked glycan intermediates displayed on the protein surface serve as quality tags. The ER folding-sensor enzyme UDP-glucose:glycoprotein glucosyltransferase (UGGT) acts as a gatekeeper in the ER quality control system by specifically catalysing monoglucosylation onto incompletely folded glycoproteins, thereby enabling them to interact with lectin-chaperone complexes. Here we characterise the dynamic structure of this enzyme. Our crystallographic data demonstrate that the sensor region is composed of four thioredoxin-like domains followed by a β-rich domain, which are arranged into a C-shaped structure with a large central cavity, while the C-terminal catalytic domain undergoes a ligand-dependent conformational alteration. Furthermore, small-angle X-ray scattering, cryo-electron microscopy and high-speed atomic force microscopy have demonstrated that UGGT has a flexible modular structure in which the smaller catalytic domain is tethered to the larger folding-sensor region with variable spatial arrangements. These findings provide structural insights into the working mechanism whereby UGGT operates as a folding-sensor against a variety of glycoprotein substrates through its flexible modular structure possessing extended hydrophobic surfaces for the recognition of unfolded substrates.