5GXZ

Crystal structure of endoglucanase CelQ from Clostridium thermocellum complexed with cellobiose and cellotriose

Summary for 5GXZ

• Entry DOI: 10.2210/pdb5gxz/pdb
• Related: 5GXX 5GXY 5GY0 5GY1
• Related PRD ID: PRD_900005 PRD_900021
• Descriptor: Glucanase, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose, ... (8 entities in total)
• Functional Keywords: cellulases, glycosyl hydrolase, hydrolase, cellulosome
• Biological source: Clostridium thermocellum
• Total number of polymer chains: 2
• Total formula weight: 141281.50

Authors

Jeng, W.Y.,Liu, C.I.,Wang, A.H.J. (deposition date: 2016-09-21, release date: 2017-09-27, Last modification date: 2024-10-23)

Primary citation

Jeng, W.Y.,Liu, C.I.,Lu, T.J.,Lin, H.J.,Wang, N.C.,Wang, A.H.
Crystal Structures of the C-Terminally Truncated Endoglucanase Cel9Q from Clostridium thermocellum Complexed with Cellodextrins and Tris.
Chembiochem, 20:295-307, 2019

PubMed Abstract: Endoglucanase CtCel9Q is one of the enzyme components of the cellulosome, which is an active cellulase system in the thermophile Clostridium thermocellum. The precursor form of CtCel9Q comprises a signal peptide, a glycoside hydrolase family 9 catalytic domain, a type 3c carbohydrate-binding module (CBM), and a type I dockerin domain. Here, we report the crystal structures of C-terminally truncated CtCel9Q (CtCel9QΔc) complexed with Tris, Tris+cellobiose, cellobiose+cellotriose, cellotriose, and cellotetraose at resolutions of 1.50, 1.70, 2.05, 2.05 and 1.75 Å, respectively. CtCel9QΔc forms a V-shaped homodimer through residues Lys529-Glu542 on the type 3c CBM, which pairs two β-strands (β4 and β5 of the CBM). In addition, a disulfide bond was formed between the two Cys535 residues of the protein monomers in the asymmetric unit. The structures allow the identification of four minus (-) subsites and two plus (+) subsites; this is important for further understanding the structural basis of cellulose binding and hydrolysis. In the oligosaccharide-free and cellobiose-bound CtCel9QΔc structures, a Tris molecule was found to be bound to three catalytic residues of CtCel9Q and occupied subsite -1 of the CtCel9Q active-site cleft. Moreover, the enzyme activity assay in the presence of 100 mm Tris showed that the Tris almost completely suppressed CtCel9Q hydrolase activity.

PubMed: 30609216
DOI: 10.1002/cbic.201800789

Experimental method

X-RAY DIFFRACTION (2.05 Å)