Uncovering the release mechanism of nucleotide import by HIV-1 capsid

Review and Perspectives on the Structure-Function Relationships of the Gag Subunits of Feline Immunodeficiency Virus

The Gag polyprotein is implied in the budding as well as the establishment of the supramolecular architecture of infectious retroviral particles. It is also involved in the early phases of the replication of retroviruses by protecting and transporting the viral genome towards the nucleus of the infected cell until its integration in the host genome. Therefore, understanding the structure-function relationships of the Gag subunits is crucial as each of them can represent a therapeutic target. Though the field has been explored for some time in the area of Human Immunodeficiency Virus (HIV), it is only in the last decade that structural data on Feline Immunodeficiency Virus (FIV) Gag subunits have emerged. As FIV is an important veterinary issue, both in domestic cats and endangered feline species, such data are of prime importance for the development of anti-FIV molecules targeting Gag. This review will focus on the recent advances and perspectives on the structure-function relationships of each subunit of the FIV Gag polyprotein.

Structure, Function, and Interactions of the HIV-1 Capsid Protein

The capsid (CA) protein of the human immunodeficiency virus type 1 (HIV-1) is an essential structural component of a virion and facilitates many crucial life cycle steps through interactions with host cell factors. Capsid shields the reverse transcription complex from restriction factors while it enables trafficking to the nucleus by hijacking various adaptor proteins, such as FEZ1 and BICD2. In addition, the capsid facilitates the import and localization of the viral complex in the nucleus through interaction with NUP153, NUP358, TNPO3, and CPSF-6. In the later stages of the HIV-1 life cycle, CA plays an essential role in the maturation step as a constituent of the Gag polyprotein. In the final phase of maturation, Gag is cleaved, and CA is released, allowing for the assembly of CA into a fullerene cone, known as the capsid core. The fullerene cone consists of ~250 CA hexamers and 12 CA pentamers and encloses the viral genome and other essential viral proteins for the next round of infection. As research continues to elucidate the role of CA in the HIV-1 life cycle and the importance of the capsid protein becomes more apparent, CA displays potential as a therapeutic target for the development of HIV-1 inhibitors.