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Chembiochem. 2017 Apr 18;18(8):764-771. doi: 10.1002/cbic.201600665. Epub 2017 Mar 22.

Insights from NMR Spectroscopy into the Conformational Properties of Man-9 and Its Recognition by Two HIV Binding Proteins.

Author information

1
Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, 8 Center Drive, Bethesda, MD, 20892, USA.
2
Structural Biology Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, 40 Convent Drive, Bethesda, MD, 20892, USA.
3
Present address: Department of Biology, SBA School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54792, Pakistan.
4
Structural Bioinformatics Core Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, 40 Convent Drive, Bethesda, MD, 20892, USA.

Abstract

Man9 GlcNAc2 (Man-9) present at the surface of HIV makes up the binding sites of several HIV-neutralizing agents and the mammalian lectin DC-SIGN, which is involved in cellular immunity and trans-infections. We describe the conformational properties of Man-9 in its free state and when bound by the HIV entry-inhibitor protein microvirin (MVN), and define the minimum epitopes of both MVN and DC-SIGN by using NMR spectroscopy. To facilitate the implementation of 3D 13 C-edited spectra to deconvolute spectral overlap and to determine the solution structure of Man-9, we developed a robust expression system for the production of 13 C,15 N-labeled glycans in mammalian cells. The studies reveal that Man-9 interacts with HIV-binding proteins through distinct epitopes and adopts diverse conformations in the bound state. In combination with molecular dynamics simulations we observed receptor-bound conformations to be sampled by Man-9 in the free state, thus suggesting a conformational selection mechanism for diverse recognition.

KEYWORDS:

NMR spectroscopy; carbohydrate recognition; glycan conformation; isotopic labeling; molecular dynamics

PMID:
28166380
PMCID:
PMC5557091
DOI:
10.1002/cbic.201600665
[Indexed for MEDLINE]
Free PMC Article

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