1cx1
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SECOND N-TERMINAL CELLULOSE-BINDING DOMAIN FROM CELLULOMONAS FIMI BETA-1,4-GLUCANASE C, NMR, 22 STRUCTURES
OverviewOverview
The 1,4-beta-glucanase CenC from Cellulomonas fimi contains two, cellulose-binding domains, CBD(N1) and CBD(N2), arranged in tandem at its, N-terminus. These homologous CBDs are distinct in their selectivity for, binding amorphous and not crystalline cellulose. Multidimensional, heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to, determine the tertiary structure of CBD(N2) in the presence of saturating, amounts of cellopentaose. A total of 1996 experimental restraints were, used to calculate an ensemble of 21 final structures for the protein., CBD(Nu2) is composed of 11 beta-strands, folded into two antiparallel, beta-sheets, with a topology of a jellyroll beta-sandwich. On the basis of, patterns of chemical shift perturbations accompanying the addition of, cellooligosaccharides, as well as the observation of intermolecular, protein-sugar NOE interactions, the cellulose-binding site of CBD(N2) was, identified as a cleft that lies across one face of the beta-sandwich. The, thermodynamic basis for the binding of cellooligosaccharides was, investigated using isothermal titration calorimetry and NMR spectroscopy., Binding is enthalpically driven and consistent with a structural model, involving hydrogen bonding between the equatorial hydroxyls of the, glucopyranosyl rings and polar amino acid side chains lining the CBD(N2), cleft. Affinity electrophoresis was used to determine that CBD(N2) also, binds soluble beta-1,4-linked polymers of glucose, including, hydroxyethylcellulose and beta-1,3-1,4-glucans. This study complements a, previous analysis of CBD(N1) [Johnson, P. E., Joshi, M. D., Tomme, P., Kilburn, D. G., and McIntosh, L. P. (1996) Biochemistry 35, 14381-14394], and demonstrates that the homologous CBDs from CenC share very similar, structures and sugar binding properties.
About this StructureAbout this Structure
1CX1 is a Single protein structure of sequence from Cellulomonas fimi. Active as Cellulase, with EC number 3.2.1.4 Full crystallographic information is available from OCA.
ReferenceReference
Structure and binding specificity of the second N-terminal cellulose-binding domain from Cellulomonas fimi endoglucanase C., Brun E, Johnson PE, Creagh AL, Tomme P, Webster P, Haynes CA, McIntosh LP, Biochemistry. 2000 Mar 14;39(10):2445-58. PMID:10704194
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