Atomic mapping of the interactions between the antiviral agent cyanovirin-N and oligomannosides by saturation-transfer difference NMR.
The minimum oligosaccharide structure required for binding to the potent HIV-inactivating protein cyanovirin-N (CV-N) was determined by saturation-transfer difference (STD) NMR spectroscopy. Despite the low molecular mass of the protein (11 kDa), STD-NMR spectroscopy allowed the precise atomic mapping of the interactions between CV-N and various di- and trimannosides, substructures of Man-9, the predominant oligosaccharide on the HIV viral surface glycoprotein gp120. Contacts with mannosides containing the terminal Manalpha(1-->2)Manalpha unit of Man-9 were observed, while (1-->3)- and (1-6)-linked di- and trimannosides showed no interactions, demonstrating that the terminal Manalpha(1-->2)Manalpha structure plays a key role in the interaction. Precise epitope mapping revealed that, for Manalpha(1-->2)ManalphaOMe, Manalpha(1-->2)Manalpha(1-->3)ManalphaOMe, and Manalpha(1-->2)Manalpha(1-->6)ManalphaOMe, the protein is in close contact with H2, H3, and H4 of the nonreducing terminal mannose unit. In contrast, the STD-NMR spectrum of the CV-N/trisaccharide Manalpha(1-->2)Manalpha(1-->2)ManalphaOMe complex was markedly different, with resonances on all sugar units displaying equal enhancements, suggesting that CV-N is able to discriminate between the three structurally related trisaccharides.
Sandström
Corine
C
Department of Chemistry, Swedish University of Agricultural Sciences, Post Office Box 7015, SE-750 07 Uppsala, Sweden. corine.sandstrom@kemi.slu.se
Berteau
Olivier
O
Gemma
Emiliano
E
Oscarson
Stefan
S
Kenne
Lennart
L
Gronenborn
Angela M
AM
D019380:Anti-HIV Agents / Q000737:chemistry / Q000378:metabolism; D000998:Antiviral Agents / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D004187:Disaccharides / Q000737:chemistry / Q000378:metabolism; D004347:Drug Interactions; D018604:Epitope Mapping / Q000379:methods*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008351:Mannans / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism
D019380:Anti-HIV Agents; D000998:Antiviral Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004187:Disaccharides; D015699:HIV Envelope Protein gp120; D008024:Ligands; D008351:Mannans; D009844:Oligosaccharides; D014312:Trisaccharides; C475461:mannosyl(9)-N-acetylglucosamine2; C028569:oligomannoside; C107733:cyanovirin N