Functional Characterisation of HIV-1 gag-pol Fusion Protein

Abstract

Among the three major genes, gag, pol, and env of the human immunodeficiency virus (HIV), the pol gene encodes at least three products, protease, reverse transcriptase (RT), and integrase, which are essential for viral replication and maturation (Steimer et al, 1986; Lilliehoj et al, 1988 ; Kohl et al, 1988; Peng et al, 1989). The expression of functional pol gene products has been proposed to include two important stages. The first is that by means of a ribosomal frameshifting mechanism gag-pol fusion protein, which contains a large portion of gag coding region and the entire pol coding region is generated. Published In vitro transcription and translation studies have shown that the gag and pol genes of HIV-1 overlap and use two different translational reading frames (Jacks et al, 1988). These studies have also shown that the gag-pol protein is created by a ribosomal ‘−1 frameshifting’ mechanism during translation, resulting in a long, fused polypeptide composed of a C-terminal-truncated gag peptide and the entire pol peptide. The second stage involves the proteolytic processing of this fusion protein to generate mature structural and functional viral components (Debouck et al, 1987; Lillehoj et al, 1988). An HIV-specific protease cleaves the fusion protein to generate matured core proteins, RT, integrase, and protease.