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Journal of Virology, December 1998, p. 9676-9682, Vol. 72, No. 12
Center for Biologics Evaluation and Research,
Food and Drug Administration, Bethesda, Maryland 20892
Received 25 June 1998/Accepted 20 August 1998
The envelope glycoprotein (Env) of human immunodeficiency virus
mediates virus entry into cells by undergoing conformational changes that lead to fusion between viral and cellular membranes. A
six-helix bundle in gp41, consisting of an interior trimeric coiled-coil core with three exterior helices packed in the grooves (core structure), has been proposed to be part of a fusion-active structure of Env (D. C. Chan, D. Fass, J. M. Berger, and
P. S. Kim, Cell 89:263-273, 1997; W. Weissenhorn, A. Dessen,
S. C. Harrison, J. J. Skehel, and D. C. Wiley, Nature
387:426-430, 1997; and K. Tan, J. Liu, J. Wang, S. Shen, and M. Lu,
Proc. Natl. Acad. Sci. USA 94:12303, 1997). We analyzed the effects
of amino acid substitutions of arginine or glutamic acid in residues in
the coiled-coil (heptad repeat) domain that line the interface between
the helices in the gp41 core structure. We found that mutations of
leucine to arginine or glutamic acid in position 556 and of alanine to
arginine in position 558 resulted in undetectable
levels of Env expression. Seven other mutations in six positions
completely abolished fusion activity despite incorporation of the
mutant Env into virions and normal gp160 processing.
Single-residue substitutions of glutamic acid at position 570 or 577 resulted in the only viable mutants among the 16 mutants studied,
although both viable mutants exhibited impaired fusion activity
compared to that of the wild type. The glutamic acid 577 mutant was
more sensitive than the wild type to inhibition by a gp41
coiled-coil peptide (DP-107) but not to that by another peptide
corresponding to the C helix in the gp41 core structure (DP-178).
These results provide insight into the gp41 fusion mechanism and
suggest that the DP-107 peptide may inhibit fusion by binding to the
homologous region in gp41, probably by forming a peptide-gp41
coiled-coil structure.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Mutational Analysis of Residues in the Coiled-Coil Domain of
Human Immunodeficiency Virus Type 1 Transmembrane Protein
gp41
*
Corresponding author. Mailing address: FDA/CBER,
HFM-413, Bldg. 29, Room 532, 29 Lincoln Dr., Bethesda, MD 20892-4555. Phone: (301) 402-3190. Fax: (301) 496-4684. E-mail:
cdweiss{at}helix.nih.gov.
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