The impact of mutations affecting highly conserved amino acids in the simian immunodeficiency virus nucleocapsid protein on virion assembly, genomic RNA packaging and viral infectivity

• Published in: Virology (New York, N.Y.) Vol. 578; pp. 163 - 170
• Main Authors: González, Silvia A., Affranchino, José L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2023
• Subjects: Amino Acid Sequence; Amino Acids - genetics; Animals; cysteine; Cysteine - genetics; domain; Gag polyprotein; Genomics; Human immunodeficiency virus 1; Infectious Disease; Mutation; nucleocapsid; Nucleocapsid protein; nucleocapsid proteins; Nucleocapsid Proteins - genetics; Nucleocapsid Proteins - metabolism; pathogenicity; polyproteins; RNA; RNA, Viral - genetics; RNA, Viral - metabolism; Simian immunodeficiency virus; Simian Immunodeficiency Virus - genetics; Simian Immunodeficiency Virus - metabolism; Viral RNA packaging; virion; Virion - genetics; Virion - metabolism; Virion assembly; virology; Virus Assembly - genetics; zinc; zinc finger motif; Virion assembly; Simian immunodeficiency virus; Gag polyprotein; Nucleocapsid protein; Viral RNA packaging
• ISSN: 0042-6822; 1096-0341; 1096-0341
• DOI: 10.1016/j.virol.2022.12.007

The nucleocapsid (NC) domain of the retroviral Gag polyproteins mediates the incorporation of the viral genomic RNA into virions. Although SIV is widely used as a model for human immunodeficiency virus type 1 (HIV-1) infections, the SIV NC has been the subject of few studies which have provided discrepant data on the relative contribution of the two NC zinc finger motifs to genomic RNA encapsidation. Here, we demonstrate that mutations affecting the first cysteine in the distal zinc finger motif (C33S) or the N-terminal NC basic domain (R7A/K8A) drastically impair virion assembly and viral RNA binding. By contrast, amino acid substitutions targeting the first cysteine of the proximal zinc finger (C12S) or the basic region connecting both zinc fingers (R29A/R30A) allow substantial particle production and genomic RNA encapsidation. Our results help define the relative contribution of the SIV NC zinc finger motifs and basic regions to the NC biological properties. •We define the relative contribution of the two zinc fingers of the SIV nucleocapsid (NC) to RNA binding and virion assembly.•The distal zinc finger is more important than the proximal motif for the biological functions of the SIV NC.•Replacement of the first cysteine in the distal zinc finger by serine drastically impairs virion assembly and RNA binding.•Mutation of the first cysteine of the proximal zinc finger slightly affects particle production and viral RNA encapsidation.•The SIV NC functions are highly sensitive to mutations of the conserved amino terminal basic residues.