5LU3

The Structure of Spirochaeta thermophila CBM64

Summary for 5LU3

• Entry DOI: 10.2210/pdb5lu3/pdb
• Descriptor: Glycoside hydrolase family 12, 3,6,9,12,15-pentaoxaoctadecan-17-amine, 4-oxobutanoic acid, ... (7 entities in total)
• Functional Keywords: cbm64 spirochaeta thermophila x-ray, hydrolase, sugar binding protein
• Biological source: Spirochaeta thermophila (strain ATCC 700085 / DSM 6578 / Z-1203)
• Total number of polymer chains: 1
• Total formula weight: 11520.20

Authors

Correia, M.A.S.,Romao, M.J.,Carvalho, A.L. (deposition date: 2016-09-07, release date: 2017-02-15, Last modification date: 2024-05-08)

Primary citation

Pires, V.M.,Pereira, P.M.,Bras, J.L.,Correia, M.,Cardoso, V.,Bule, P.,Alves, V.D.,Najmudin, S.,Venditto, I.,Ferreira, L.M.,Romao, M.J.,Carvalho, A.L.,Fontes, C.M.,Prazeres, D.M.
Stability and Ligand Promiscuity of Type A Carbohydrate-binding Modules Are Illustrated by the Structure of Spirochaeta thermophila StCBM64C.
J. Biol. Chem., 292:4847-4860, 2017

PubMed Abstract: Deconstruction of cellulose, the most abundant plant cell wall polysaccharide, requires the cooperative activity of a large repertoire of microbial enzymes. Modular cellulases contain non-catalytic type A carbohydrate-binding modules (CBMs) that specifically bind to the crystalline regions of cellulose, thus promoting enzyme efficacy through proximity and targeting effects. Although type A CBMs play a critical role in cellulose recycling, their mechanism of action remains poorly understood. Here we produced a library of recombinant CBMs representative of the known diversity of type A modules. The binding properties of 40 CBMs, in fusion with an N-terminal GFP domain, revealed that type A CBMs possess the ability to recognize different crystalline forms of cellulose and chitin over a wide range of temperatures, pH levels, and ionic strengths. A CBM64, in particular, displayed plasticity in its capacity to bind both crystalline and soluble carbohydrates under a wide range of extreme conditions. The structure of CBM64C revealed an untwisted, flat, carbohydrate-binding interface comprising the side chains of four tryptophan residues in a co-planar linear arrangement. Significantly, two highly conserved asparagine side chains, each one located between two tryptophan residues, are critical to insoluble and soluble glucan recognition but not to bind xyloglucan. Thus, CBM64 compact structure and its extended and versatile ligand interacting platform illustrate how type A CBMs target their appended plant cell wall-degrading enzymes to a diversity of recalcitrant carbohydrates under a wide range of environmental conditions.

PubMed: 28179427
DOI: 10.1074/jbc.M116.767541

Experimental method

X-RAY DIFFRACTION (1.5 Å)