title: Coding sequences upstream of the human immunodeficiency virus type 1 reverse transcriptase domain in Gag-Pol are not essential for incorporation of the Pr160(gag-pol) into virus particles.
abstract: Incorporation of the human immunodeficiency virus type 1 (HIV-1) Gag-Pol into virions is thought to be mediated by the N-terminal Gag domain via interaction with the Gag precursor. However, one recent study has demonstrated that the murine leukemia virus Pol can be incorporated into virions independently of Gag-Pol expression, implying a possible interaction between the Pol and Gag precursor. To test whether the HIV-1 Pol can be incorporated into virions on removal of the N-terminal Gag domain and to define sequences required for the incorporation of Gag-Pol into virions in more detail, a series of HIV Gag-Pol expression plasmids with various extensive deletions in the region upstream of the reverse transcriptase (RT) domain was constructed, and viral incorporation of the Gag-Pol deletion mutants was examined by cotransfecting 293T cells with a plasmid expressing Pr55(gag). Analysis indicated that deletion of the N-terminal two-thirds of the gag coding region did not significantly affect the incorporation of Gag-Pol into virions. In contrast, Gag-Pol proteins with deletions covering the capsid (CA) major homology regions and the adjacent C-terminal CA regions were impaired with respect to assembly into virions. However, Gag-Pol with sequences deleted upstream of the protease, or of the RT domain but retaining 15 N-terminal gag codons, could still be rescued into virions at a level about 20% of the wild-type level. When assayed in a nonmyristylated Gag-Pol context, all of the Gag-Pol deletion mutants were incorporated into virions at a level comparable to their myristylated counterparts, suggesting that the incorporation of the Gag-Pol deletion mutants into virions is independent of the N-terminal myristylation signal.
authors.affiliation: Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Department of Medical Research and Education, Taipei Veterans General Hospital, Taiwan.
authors.forename: Hsu-Chen
authors.initials: HC
authors.lastname: Chiu
authors.forename: Szu-Yung
authors.initials: SY
authors.lastname: Yao
authors.forename: Chin-Tien
authors.initials: CT
authors.lastname: Wang
mesh_terms: D002213:Capsid / Q000235:genetics; D002460:Cell Line; D017353:Gene Deletion; D015683:Gene Products, gag / Q000235:genetics* / Q000378:metabolism; D015684:Gene Products, pol / Q000235:genetics*; D054303:HIV Reverse Transcriptase / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D019814:Myristic Acid; D010957:Plasmids; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D019065:Virus Assembly; D054301:gag Gene Products, Human Immunodeficiency Virus; D054302:pol Gene Products, Human Immunodeficiency Virus
chemical_list: D015683:Gene Products, gag; D015684:Gene Products, pol; D011498:Protein Precursors; D054301:gag Gene Products, Human Immunodeficiency Virus; C059767:p55 gag precursor protein, Human immunodeficiency virus 1; D054302:pol Gene Products, Human Immunodeficiency Virus; C091950:pr160 gag-pol precursor protein, Human immunodeficiency virus 1; D019814:Myristic Acid; D054303:HIV Reverse Transcriptase