1iiy
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(New page: 200px<br /> <applet load="1iiy" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iiy" /> '''SOLUTION NMR STRUCTURE OF COMPLEX OF 1:2 CY...)
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Revision as of 12:04, 8 November 2007
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SOLUTION NMR STRUCTURE OF COMPLEX OF 1:2 CYANOVIRIN-N:MAN-ALPHA1,2-MAN-ALPHA RESTRAINED REGULARIZED MEAN COORDINATES
Overview
BACKGROUND: Cyanovirin-N (CVN) is a novel, 11 kDa cyanobacterial protein, that potently inhibits viral entry by diverse strains of HIV through, high-affinity carbohydrate-mediated interactions with the viral envelope, glycoprotein gp120. CVN contains two symmetry-related carbohydrate binding, sites of differing affinities that selectively bind to Man(8) D1D3 and, Man(9) with nanomolar affinities, the carbohydrates that also mediate, CVN:gp120 binding. High-resolution structural studies of CVN in complex, with a representative oligosaccharide are desirable for understanding the, structural basis for this unprecedented specificity. RESULTS: We have, determined by multidimensional heteronuclear NMR spectroscopy the, three-dimensional solution structure of CVN in complex with two, equivalents of the disaccharide Manalpha1-2Manalpha, a high-affinity, ligand which represents the terminal-accessible disaccharide present in, Man(8) D1D3 and Man(9). The structure reveals that the bound disaccharide, adopts the stacked conformation, thereby explaining the selectivity for, Man(8) D1D3 and Man(9) over other oligomannose structures, and presents, two novel carbohydrate binding sites that account for the differing, affinities of the two sites. The high-affinity site comprises a deep, pocket that nearly envelops the disaccharide, while the lower-affinity, site comprises a semicircular cleft that partially surrounds the, disaccharide. The approximately 40 A spacing of the two binding sites, provides a simple model for CVN:gp120 binding. CONCLUSIONS: The, CVN:Manalpha1-2Manalpha complex provides the first high-resolution, structure of a mannose-specific protein-carbohydrate complex with, nanomolar affinity and presents a new carbohydrate binding motif, as well, as a new class of carbohydrate binding protein, that facilitates divalent, binding via a monomeric protein.
About this Structure
1IIY is a Single protein structure of sequence from Nostoc ellipsosporum. Full crystallographic information is available from OCA.
Reference
Solution structure of a cyanovirin-N:Man alpha 1-2Man alpha complex: structural basis for high-affinity carbohydrate-mediated binding to gp120., Bewley CA, Structure. 2001 Oct;9(10):931-40. PMID:11591348
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