Distinct glycan topology for avian and human sialopentasaccharide receptor analogues upon binding different hemagglutinins: a molecular dynamics perspective.
Hemagglutinin (HA) binds to sialylated glycans exposed on the host cell surface in the initial stage of avian influenza virus infection. It has been previously hypothesized that glycan topology plays a critical role in the human adaptation of avian flu viruses, such as the potentially pandemic H5N1. Comparative molecular dynamics studies are complementary to experimental techniques, including glycan microarray, to understand the mechanism of species-specificity switch better. The examined systems comprise explicitly solvated trimeric forms of avian H3, H5, and swine H9 in complex with avian and human glycan receptor analogues--LSTa (alpha-2,3-linked lactoseries tetrasaccharide a) and LSTc (alpha-2,6-linked lactoseries tetrasaccharide c), respectively. The glycans adopted distinct topological profiles with inducible torsional angles when bound to different HAs. The corresponding receptor binding domain amino acid contact profiles were also distinct. Avian H5 was able to accommodate LSTc in a tightly "folded umbrella"-like topology through interactions with all five sugar residues. After considering conformational entropy, the relative binding free-energy changes, calculated using the molecular mechanics-generalized Born surface area technique, were in agreement with previous experimental findings and provided insights on electrostatic, van der Waals, desolvation, and entropic contributions to HA-glycan interactions. The topology profile and the relative abundance of free glycan receptors may influence receptor binding kinetics. Glycan composition and topological changes upon binding different HAs may be important determinants in species-specificity switch.
Xu
Dong
D
National Biomedical Computation Resource, University of California San Diego, La Jolla, CA 92093-0505, USA. dxu@mccammon.ucsd.edu
Newhouse
E Irene
EI
Amaro
Rommie E
RE
Pao
Hsing C
HC
Cheng
Lily S
LS
Markwick
Phineus R L
PR
McCammon
J Andrew
JA
Li
Wilfred W
WW
Arzberger
Peter W
PW
D000818:Animals; D001717:Birds / Q000378:metabolism*; D003198:Computer Simulation; D019277:Entropy; D005690:Galactose / Q000378:metabolism; D006388:Hemagglutinins / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012996:Solutions
D006388:Hemagglutinins; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D012996:Solutions; D019158:N-Acetylneuraminic Acid; D005690:Galactose