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Molecular basis for the preferential recognition of β1,3‐1,4‐glucans by the family 11 carbohydrate‐binding module from Clostridium thermocellum

DOI: 10.1111/febs.15162 DOI Help

Authors: Diana O. Ribeiro (UCIBIO, Universidade NOVA de Lisboa) , Aldino Viegas (UCIBIO, Universidade NOVA de Lisboa) , Virgínia M. R. Pires (CIISA ‐ Faculdade de Medicina Veterinária, Universidade de Lisboa) , João Medeiros‐silva (UCIBIO, Universidade NOVA de Lisboa) , Pedro Bule (CIISA - Faculdade de Medicina Veterinária, Universidade de Lisboa) , Wengang Chai (Imperial College London) , Filipa Marcelo (UCIBIO, Universidade NOVA de Lisboa) , Carlos M. G. A. Fontes (CIISA - Faculdade de Medicina Veterinária, Universidade de Lisboa; NZYTech Genes & Enzymes) , Eurico J. Cabrita (UCIBIO, Universidade NOVA de Lisboa) , Angelina S. Palma (UCIBIO, Universidade NOVA de Lisboa) , Ana Luisa Carvalho (UCIBIO, Universidade NOVA de Lisboa)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Febs Journal , VOL 40

State: Published (Approved)
Published: December 2019
Diamond Proposal Number(s): 16609

Abstract: Understanding the specific molecular interactions between proteins and β1,3‐1,4‐mixed‐linked d‐glucans is fundamental to harvest the full biological and biotechnological potential of these carbohydrates and of proteins that specifically recognize them. The family 11 carbohydrate‐binding module from Clostridium thermocellum (CtCBM11) is known for its binding preference for β1,3‐1,4‐mixed‐linked over β1,4‐linked glucans. Despite the growing industrial interest of this protein for the biotransformation of lignocellulosic biomass, the molecular determinants of its ligand specificity are not well defined. In this report, a combined approach of methodologies was used to unravel, at a molecular level, the ligand recognition of CtCBM11. The analysis of the interaction by carbohydrate microarrays and NMR and the crystal structures of CtCBM11 bound to β1,3‐1,4‐linked glucose oligosaccharides showed that both the chain length and the position of the β1,3‐linkage are important for recognition, and identified the tetrasaccharide Glcβ1,4Glcβ1,4Glcβ1,3Glc sequence as a minimum epitope required for binding. The structural data, along with site‐directed mutagenesis and ITC studies, demonstrated the specificity of CtCBM11 for the twisted conformation of β1,3‐1,4‐mixed‐linked glucans. This is mediated by a conformation–selection mechanism of the ligand in the binding cleft through CH‐π stacking and a hydrogen bonding network, which is dependent not only on ligand chain length, but also on the presence of a β1,3‐linkage at the reducing end and at specific positions along the β1,4‐linked glucan chain. The understanding of the detailed mechanism by which CtCBM11 can distinguish between linear and mixed‐linked β‐glucans strengthens its exploitation for the design of new biomolecules with improved capabilities and applications in health and agriculture.

Journal Keywords: carbohydrate specificity; carbohydrate‐binding module; cellulosome; Clostridium thermocellum; β1,3‐1,4‐mixed‐linked glucans

Diamond Keywords: Bacteria; Enzymes; Biofuel

Subject Areas: Biology and Bio-materials, Energy, Environment

Instruments: I02-Macromolecular Crystallography

Added On: 05/02/2020 14:15

Discipline Tags:

Bioenergy Earth Sciences & Environment Biotechnology Sustainable Energy Systems Energy Climate Change Structural biology Engineering & Technology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)