title: The influence of N-linked glycans on the molecular dynamics of the HIV-1 gp120 V3 loop.
abstract: N-linked glycans attached to specific amino acids of the gp120 envelope trimer of a HIV virion can modulate the binding affinity of gp120 to CD4, influence coreceptor tropism, and play an important role in neutralising antibody responses. Because of the challenges associated with crystallising fully glycosylated proteins, most structural investigations have focused on describing the features of a non-glycosylated HIV-1 gp120 protein. Here, we use a computational approach to determine the influence of N-linked glycans on the dynamics of the HIV-1 gp120 protein and, in particular, the V3 loop. We compare the conformational dynamics of a non-glycosylated gp120 structure to that of two glycosylated gp120 structures, one with a single, and a second with five, covalently linked high-mannose glycans. Our findings provide a clear illustration of the significant effect that N-linked glycosylation has on the temporal and spatial properties of the underlying protein structure. We find that glycans surrounding the V3 loop modulate its dynamics, conferring to the loop a marked propensity towards a more narrow conformation relative to its non-glycosylated counterpart. The conformational effect on the V3 loop provides further support for the suggestion that N-linked glycosylation plays a role in determining HIV-1 coreceptor tropism.
authors.affiliation: South African National Bioinformatics Institute, South African Medical Research Council Bioinformatics Unit, University of the Western Cape, Cape Town, South Africa.
authors.forename: Natasha T
authors.initials: NT
authors.lastname: Wood
authors.forename: Elisa
authors.initials: E
authors.lastname: Fadda
authors.forename: Robert
authors.initials: R
authors.lastname: Davis
authors.forename: Oliver C
authors.initials: OC
authors.lastname: Grant
authors.forename: Joanne C
authors.initials: JC
authors.lastname: Martin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Woods
authors.forename: Simon A
authors.initials: SA
authors.lastname: Travers
mesh_terms: D006031:Glycosylation; D015699:HIV Envelope Protein gp120 / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D010446:Peptide Fragments / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D011134:Polysaccharides