title: Structural comparison of HIV-1 envelope spikes with and without the V1/V2 loop.
abstract: We have used cryoelectron tomography of vitreous-ice-embedded HIV-1 virions to compare the envelope (Env) spikes of a wild-type strain with those of a mutant strain in which the V1/V2 loop has been deleted. Deletion of V1/V2 results in a spike with far more structural heterogeneity than is observed in the wild type, likely reflecting greatly enhanced gp120 protomer flexibility. A major difference between the two forms is a pronounced loss of mass from the "peak" of the native Env spike. The apparent loss of contact among three gp120 protomers likely accounts for the more open structure, heterogeneity in configuration, and previous observations that broadly neutralizing epitopes and reactive sites on other structural elements are more exposed in such constructs.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA.
authors.forename: Guiqing
authors.initials: G
authors.lastname: Hu
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Taylor
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Roux
mesh_terms: D020285:Cryoelectron Microscopy; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D015497:HIV-1 / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D008954:Models, Biological; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure; D017384:Sequence Deletion
chemical_list: D015699:HIV Envelope Protein gp120; D050505:Mutant Proteins; C514793:gp120 protein, Human immunodeficiency virus 1