title: Atomic structure of the ectodomain from HIV-1 gp41.
abstract: Fusion of viral and cellular membranes by the envelope glycoprotein gp120/gp41 effects entry of HIV-1 into the cell. The precursor, gp160, is cleaved post-translationally into gp120 and gp41 which remain non-covalently associated. Binding to both CD4 and a co-receptor leads to the conformational changes in gp120/gp41 needed for membrane fusion. We used X-ray crystallography to determine the structure of the protease-resistant part of a gp41 ectodomain solubilized with a trimeric GCN4 coiled coil in place of the amino-terminal fusion peptide. The core of the molecule is found to be an extended, triple-stranded alpha-helical coiled coil with the amino terminus at its tip. A carboxy-terminal alpha-helix packs in the reverse direction against the outside of the coiled coil, placing the amino and carboxy termini near each other at one end of the long rod. These features, and the existence of a similar reversal of chain direction in the fusion pH-induced conformation of influenza virus HA2 and in the transmembrane subunit of Moloney murine leukaemia virus (Fig. 1a-d), suggest a common mechanism for initiating fusion.
authors.affiliation: Laboratory of Molecular Medicine, The Children's Hospital, Boston, Massachusetts 02215, USA.
authors.forename: W
authors.initials: W
authors.lastname: Weissenhorn
authors.forename: A
authors.initials: A
authors.lastname: Dessen
authors.forename: S C
authors.initials: SC
authors.lastname: Harrison
authors.forename: J J
authors.initials: JJ
authors.lastname: Skehel
authors.forename: D C
authors.initials: DC
authors.lastname: Wiley
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000235:genetics; D015497:HIV-1 / Q000737:chemistry*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D015700:HIV Envelope Protein gp41; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases