Nuclear import of APOBEC3F-labeled HIV-1 preintegration complexes

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Human cytidine deaminases APOBEC3F (A3F) and APOBEC3G (A3G) are critical host factors that restrict retroviral replication by incorporating into virions.
• Understanding the intracellular trafficking and nuclear import of preintegration complexes (PICs) is crucial for deciphering HIV-1 replication and host-pathogen interactions.

Purpose of the Study:

• To develop tools for visualizing HIV-1 PICs within infected cells.
• To investigate the mechanisms governing the nuclear import of PICs, including the roles of APOBEC3 proteins, reverse transcription, and viral capsid structure.

Main Methods:

• Utilized yellow fluorescent protein (YFP)-tagged APOBEC3F and APOBEC3G to label and visualize HIV-1 PICs in infected cells.
• Examined the dependence of PIC nuclear import on nuclear pore protein Nup153 and TNPO3.
• Assessed the impact of reverse transcription and viral capsid mutations on PIC nuclear import and nuclear envelope association.

Main Results:

• A3F-YFP and A3G-YFP labeling enabled visualization of PICs in the nucleus, dependent on Nup153.
• Nuclear import of PICs was independent of reverse transcription, viral core uncoating, and the central DNA flap.
• PIC nuclear import and association with the nuclear envelope were sensitive to viral capsid stability, with mutations significantly reducing these processes.
• Nuclear PICs were observed in proximity to the nuclear envelope, not distributed throughout the nucleus.

Conclusions:

• APOBEC3 proteins can serve as effective tools for tracking HIV-1 PICs during the early stages of infection.
• HIV-1 PIC nuclear import is a complex process influenced by viral capsid integrity and nuclear pore interactions, independent of reverse transcription.
• These findings provide novel insights into the dynamics of HIV-1 PICs and offer new avenues for studying retroviral nuclear entry.