Characterization of Human Immunodeficiency Virus Type 1 Pr55gagMembrane Association in a Cell-Free System: Requirement for a C-Terminal Domain

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 91; no. 10; pp. 4594 - 4598
• Main Authors: Platt, Emily J., Haffar, Omar K.
• Format: Journal Article
• Language: English
• Published: National Academy of Sciences of the United States of America 10.05.1994
• Subjects: Amino acids; Basic amino acids; Cell membranes; Codons; HIV 1; P branes; Protein precursors; Proteins; Truncation; Virions
• ISSN: 0027-8424; 1091-6490

Association of the human immunodeficiency virus type 1 (HIV-1) gag polyprotein precursor with cellular membranes is necessary for assembly of virions. We used in vitro synthesized HIV-1 gag to study its association with isolated cellular membranes. Rabbit reticulocyte lysates programmed with HIV-1 gag mRNA incorporated [35S]methionine and [3H]myristate into two predominant species of 55 kDa and 40 kDa. Radioimmunoprecipitation with HIV-1-specific antibodies suggested that the 55-kDa protein represented the polyprotein precursor (Pr55gag), while the 40-kDa protein was a mixture of N- or C-terminal truncations of the gag precursor. The Pr55gagprotein bound to cellular membranes, while the 40-kDa mixed protein species did not. Membrane binding studies with C terminus-truncated and point mutants revealed that the seven-amino acid sequence located between the two Cys-His arrays in the nucleocapsid region was necessary for stable association to occur. Therefore, we propose that signals in addition to myristate are required for the membrane association of HIV-1 gag proteins and that these signals include a domain in the nucleocapsid protein.