Nucleic acid chaperone activity of retroviral nucleocapsid proteins

Abstract

This work focuses on the nucleic acid chaperone activity of retroviral nucleocapsid (NC) proteins. We use the single molecule experiments to investigate the properties of human immunodeficiency virus type 1 (HIV-1). In addition, by comparing with feline immunodeficiency virus (FIV) NC and mutating important residues, we specify the function of each structural element of interest. As an efficient nucleic acid chaperone protein, the HIV-1 NC protein facilitates the rearrangement of nucleic acid secondary structure during reverse transcription and recombination, which are critical components of retroviral replication. The biophysical basis for NC's chaperone activity includes the ability to strongly aggregate nucleic acids, destabilize nucleic acid secondary structure, and facilitate rapid protein-nucleic acid interaction kinetics. HIV-1 NC contains only 55 amino acids, with 11 basic residues throughout its structure as well as two zinc fingers, each having a single aromatic residue (F16 and W37), which is highly conserved among retroviral NC proteins. Despite its simple structure, HIV-1 NC facilitates nucleic acid rearrangement efficiently.