Cryo-EM structure of a native, fully glycosylated, cleaved HIV-1 envelope trimer.

The envelope glycoprotein trimer (Env) on the surface of HIV-1 recognizes CD4(+) T cells and mediates viral entry. During this process, Env undergoes substantial conformational rearrangements, making it difficult to study in its native state. Soluble stabilized trimers have provided valuable insights into the Env structure, but they lack the hydrophobic membrane proximal external region (MPER, an important target of broadly neutralizing antibodies), the transmembrane domain, and the cytoplasmic tail. Here we present (i) a cryogenic electron microscopy (cryo-EM) structure of a clade B virus Env, which lacks only the cytoplasmic tail and is stabilized by the broadly neutralizing antibody PGT151, at a resolution of 4.2 angstroms and (ii) a reconstruction of this form of Env in complex with PGT151 and MPER-targeting antibody 10E8 at a resolution of 8.8 angstroms. These structures provide new insights into the wild-type Env structure.