title: A trimeric structural domain of the HIV-1 transmembrane glycoprotein.
abstract: Infection with HIV-1 is initiated by fusion of cellular and viral membranes. The gp41 subunit of the HIV-1 envelope plays a major role in this process, but the structure of gp41 is unknown. We have identified a stable, proteinase-resistant structure comprising two peptides, N-51 and C-43, derived from a recombinant protein fragment of the gp41 ectodomain. In isolation, N-51 is predominantly aggregated and C-43 is unfolded. When mixed, however, these peptides associate to form a stable, alpha-helical, discrete trimer of heterodimers. Proteolysis experiments indicate that the relative orientation of the N-51 and C-43 helices in the complex is antiparallel. We propose that N-51 forms an interior, parallel, homotrimeric, coiled-coil core, against which three C-43 helices pack in an antiparallel fashion. We suggest that this alpha-helical, trimeric complex is the core of the fusion-competent state of the HIV-1 envelope.
authors.affiliation: Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge 02142, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lu
authors.forename: S C
authors.initials: SC
authors.lastname: Blacklow
authors.forename: P S
authors.initials: PS
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D010450:Endopeptidases / Q000737:chemistry; D015726:Giant Cells / Q000737:chemistry; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000648:ultrastructure*; D015497:HIV-1 / Q000737:chemistry* / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000648:ultrastructure; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D015699:HIV Envelope Protein gp120; D008562:Membrane Glycoproteins; D010455:Peptides; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; D011392:Proline; D010450:Endopeptidases