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J. Virol., 08 1997, 5723-5732, Vol 71, No. 8
N Sheng, SC Pettit, RJ Tritch, DH Ozturk, MM Rayner, R Swanstrom and S Erickson- Viitanen
During human immunodeficiency virus type 1 (HIV-1) virion assembly,
cleavage of the Gag precursor by the viral protease results in the
transient appearance of a nucleocapsid-p1-p6 intermediate product
designated p15NC. Utilizing the p15NC precursor protein produced with an in
vitro transcription-translation system or purified after expression in
Escherichia coli, we have demonstrated that RNA is required for efficient
cleavage of HIV p15NC. Gel mobility shift and nitrocellulose filter binding
experiments indicate that purified p15NC protein specifically binds its
corresponding mRNA with an estimated Kd of 1.5 nM. Binding was not affected
by the presence or absence of zinc or EDTA. Moreover, mutagenesis of the
cysteine residues within either of the two Cys-His arrays had no effect on
RNA binding or on RNA- dependent cleavage by the viral protease. In
contrast, decreased binding of RNA and diminished susceptibility to
cleavage in vitro were observed with p15NC-containing mutations in one or
more residues within the triplet of basic amino acids present in the region
between the two zinc fingers. In addition, we found that 21- to 24-base DNA
and RNA oligonucleotides of a particular sequence and secondary structure
could substitute for p15 RNA in the enhancement of p15NC cleavage. Virus
particles carrying a mutation in the triplet of NC basic residues (P3BE)
show delayed cleavage of p15NC and a defect in core formation despite the
eventual appearance of fully processed virion protein. These results define
determinants of the p15NC-RNA interaction that lead to enhanced
protease-mediated cleavage and demonstrate the importance of the triplet of
basic residues in formation of the virus core.
Copyright © 1997, American Society for Microbiology
Determinants of the human immunodeficiency virus type 1 p15NC-RNA interaction that affect enhanced cleavage by the viral protease
Molecular Biology Department, The DuPont Merck Pharmaceutical Co., Wilmington, Delaware 19880-0336, USA.
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