Natl Conf Hum Retroviruses Relat Infect (1st). 1993 Dec 12-16;:127.
Point mutations were introduced into a full length HIV-1 proviral clone
(pNL4-3) to investigate the biological significance of a conserved amino
acid sequence (PTAPP). This sequence is located near the C-terminus of
Gag precursors in most lentiviruses and all HIV-1 strains. Mutants
containing the following amino acid substitutions for the PTAPP coding
sequence were constructed: LTAPP, PTALP, PTAPL, PAAPP, PTNPP, and LTALL.
Effects on full- length genomic RNA content and viral infectivity were
determined. Upon transfection into HeLa cells, all the mutant proviruses
produced virus-like particles with properly processed p7NC, p24CA,
gp120SU and functional RT and Pr. The LTALL mutant produced
approximately 20-fold less virus than wild-type and the other mutants.
Mutant viral stocks, normalized on the basis of p24CA content, were
analyzed for infectivity in H9 cells and for genomic RNA by Northern
analysis. The infectivities ranged from near wild- type levels to
non-infectious in the following order: wild- type greater than or equal
to PTAPL, PAAPP greater than LTAPP, PTALP, PTNPP greater than LTALL. In
most cases, the reduction of mutant virus infectious titer appeared to
parallel the reduction in full length genomic RNA content. The data
suggest that single amino acid substitutions in the PTAPP sequence of
the Gag Precursor (p6 domain) can reduce the efficiency of genomic RNA
packaging or protection without influencing particle production or
infectivity. However, multiple mutations in this region (LTALL) can
result in the production of non-infectious, RNA-deficient particles,
similar to those observed from HIV-1 ZN++-finger mutants.
Amino Acid Sequence Blotting, Northern Gene Products, gag/*GENETICS
Hela Cells Human HIV Protease/GENETICS HIV-1/ENZYMOLOGY/*GENETICS
Molecular Sequence Data *Mutagenesis RNA-Directed DNA
Polymerase/GENETICS Transfection ABSTRACT