INCORPORATION OF EXCESS WILD-TYPE AND MUTANT TRNA(3)(LYS) INTO HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Human immunodeficiency virus (HIV) particles produced in COS-7 cells t ransfected with HIV type 1 (HIV-1) proviral DNA contain 8 molecules of tRNA(3)(Lys) per 2 molecules of genomic RNA and 12 molecules of tRNA( 1,2)(Lys) per 2 molecules of genomic RNA. When COS-7 cells are transfe cted with a plasmid containing both HIV-1 proviral DNA and a human tRN A(3)(Lys) gene, there is a large increase in the amount of cytoplasmic tRNA(3)(Lys) per microgram of total cellular RNA, and the tRNA(3)(Lys ) content in the virus increases from 8 to 17 molecules per 2 molecule s of genomic RNA. However, the total number of tRNA(Lys) molecules per 2 molecules of genomic RNA remains constant at 20; i.e., the viral tR NA(1,2)(Lys); content decreases from 12 to 3 molecules per 2 molecules of genomic RNA. All detectable tRNA(3)(Lys) is aminoacylated in the c ytoplasm of infected cells and deacylated in the virus. When COS-7 cel ls are transfected with a plasmid containing both HIV-1 proviral DNA a nd a mutant amber suppressor tRNA(3)(Lys) gene (in which the anticodon is changed from TTT to CTA), there is also a large increase in the re lative concentration of cytoplasmic tRNA(3)(Lys), and the tRNA(3)(Lys) content in the virus increases from 8 to 15 molecules per 2 molecules of genomic RNA, with a decrease in viral tRNA(1,2)(Lys) from 12 to 5 molecules per 2 molecules of genomic RNA. Thus, the total number of mo lecules of tRNA(Lys) in the virion remains at 20. The alteration of th e anticodon has little effect on the viral packaging of this mutant tR NA in spite of the fact that it no longer contains the modified base m cm (5)s(2)U at position 34 and its ability to be aminoacylated is sign ificantly impaired compared with that of wild-type tRNA(3)(Lys). Viral particles which have incorporated either excess wild-type tRNA(3)(Lys ) or mutant suppressor tRNA(3)(Lys) show no differences in viral infec tivity compared with wild-type HIV-1.