Three-dimensional solution structure of the 44 kDa ectodomain of SIV gp41

EMBO J. 1998 Aug 17;17(16):4572-84. doi: 10.1093/emboj/17.16.4572.


The solution structure of the ectodomain of simian immunodeficiency virus (SIV) gp41 (e-gp41), consisting of residues 27-149, has been determined by multidimensional heteronuclear NMR spectroscopy. SIV e-gp41 is a symmetric 44 kDa trimer with each subunit consisting of antiparallel N-terminal (residues 30-80) and C-terminal (residues 107-147) helices connected by a 26 residue loop (residues 81-106). The N-terminal helices of each subunit form a parallel coiled-coil structure in the interior of the complex which is surrounded by the C-terminal helices located on the exterior of the complex. The loop region is ordered and displays numerous intermolecular and non-sequential intramolecular contacts. The helical core of SIV e-gp41 is similar to recent X-ray structures of truncated constructs of the helical core of HIV-1 e-gp41. The present structure establishes unambiguously the connectivity of the N- and C-terminal helices in the trimer, and characterizes the conformation of the intervening loop, which has been implicated by mutagenesis and antibody epitope mapping to play a key role in gp120 association. In conjunction with previous studies, the solution structure of the SIV e-gp41 ectodomain provides insight into the binding site of gp120 and the mechanism of cell fusion. The present structure of SIV e-gp41 represents one of the largest protein structures determined by NMR to date.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Cell Fusion
  • HIV Envelope Protein gp120 / chemistry
  • HIV Envelope Protein gp41 / chemistry
  • HIV Envelope Protein gp41 / genetics
  • Hemagglutinin Glycoproteins, Influenza Virus / chemistry
  • Magnetic Resonance Spectroscopy
  • Membrane Glycoproteins / chemistry*
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Structure, Secondary
  • Retroviridae Proteins / chemistry*
  • Sequence Homology, Amino Acid
  • Solutions
  • Static Electricity


  • HIV Envelope Protein gp120
  • HIV Envelope Protein gp41
  • Hemagglutinin Glycoproteins, Influenza Virus
  • Membrane Glycoproteins
  • Retroviridae Proteins
  • SIV envelope protein gp41
  • Solutions