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J. Virol., Jan 1996, 248-254, Vol 70, No. 1
C Yang and RW Compans
It was previously reported that truncation or proteolytic removal of the
C-terminal 16 amino acids (the R peptide) from the cytoplasmic tail of the
murine leukemia virus (MuLV) envelope protein greatly increases its fusion
activity. In this study, to investigate the specificity of the effect of
the R peptide on the fusion activity of viral envelope proteins, we
expressed simian immunodeficiency virus (SIV)-MuLV chimeric proteins in
which the entire cytoplasmic tail of the SIV envelope protein was replaced
by either the full-length MuLV cytoplasmic tail or a truncated MuLV
cytoplasmic tail with the R peptide deleted. Extensive fusion of
CD4-positive cells with the chimeric protein containing a truncated MuLV
cytoplasmic tail was observed. In contrast, no cell fusion activity was
found for the chimeric protein with a full-length MuLV cytoplasmic tail. We
constructed another SIV-MuLV chimeric protein in which the MuLV R peptide
was added to an SIV envelope protein cytoplasmic tail 17 amino acids from
its membrane-spanning domain. No fusion activity was observed within this
construct, while the corresponding truncated SIV envelope protein lacking
the R peptide showed extensive fusion activity. No significant difference
in the transport or surface expression was observed among the various
SIV-MuLV chimeric proteins and the truncated SIV envelope protein. Our
results thus demonstrate that the MuLV R peptide has profound inhibitory
effects on virus- induced cell fusion, not only with MuLV but also in a
distantly related retroviral envelope protein which utilizes a different
receptor and fuses different cell types.
Copyright © 1996, American Society for Microbiology
Analysis of the cell fusion activities of chimeric simian immunodeficiency virus-murine leukemia virus envelope proteins: inhibitory effects of the R peptide
Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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