Association of human mitochondrial lysyl-tRNA synthetase with HIV-1 GagPol does not require other viral proteins

Area of Science:

• Molecular Biology
• Virology
• Biochemistry

Background:

• Human cells express cytoplasmic (cLysRS) and mitochondrial (mLysRS) lysyl-tRNA synthetase from a single gene.
• HIV-1 infection involves selective packaging of mLysRS and tRNA^Lys isoacceptors into viral particles, mediated by the GagPol polyprotein precursor.

Purpose of the Study:

• To investigate the role of other viral proteins in the selective hijacking of mLysRS by HIV-1.
• To reconstitute the HIV-1 tRNA₃^Lys packaging complex in vitro.

Main Methods:

• Screening of all HIV-1 viral proteins for interaction with mLysRS.
• Analysis of mLysRS association with the viral packaging complex.
• Formation of a ternary complex using purified mLysRS, Pol domain of GagPol, and tRNA₃^Lys.

Main Results:

• Viral proteins Vpr and Rev were found to potentially interact with mLysRS.
• This interaction between Vpr/Rev and mLysRS does not occur at the level of mLysRS assembly into the packaging complex.
• A ternary complex mimicking the packaging complex was formed by mLysRS, the Pol domain of GagPol, and tRNA₃^Lys.

Conclusions:

• While Vpr and Rev interact with mLysRS, they are not essential for its selective packaging into HIV-1 particles.
• The GagPol polyprotein precursor's Pol domain, mLysRS, and tRNA₃^Lys form a complex that mimics the in vivo viral packaging mechanism.