Natl Conf Hum Retroviruses Relat Infect (1st). 1993 Dec 12-16;:128.

The transcription initiation primer for HIV-1 is a specific cellular tRNA species, tRNALys,3. We have used several techniques to assess the binding of tRNA to HIV-1 reverse transcriptase (RT). This binding was found to be non- selective, with all tRNA isoacceptors, including primer tRNALys,3 binding with apparently equal affinity (KD approximately 40nM). In addition, RT-bound 32P-tRNALys,3 was as readily displaced by total unfractionated tRNa as by purified unlabelled primer tRNALys,3. RT also bound HIV-1 genomic RNA transcripts comprising 5'-LTR sequences, including the primer binding sequence (PBS). Again, no selectivity in binding was noted, with both sense and antisense RNA binding equally well. However, the concomitant presence of viral genomic RNA resulted in up to 5-fold increases in the binding of primer tRNALys,3 by RT at subsaturating levels of tRNA. Incubation of labelled primer tRNA with RT and viral genomic RNA transcripts, in the absence of any other viral proteins, resulted in the association of primer with the genomic sense RNA, but not with the antisense RNA. These results imply that RT alone may be sufficient to place primer tRNA on HIV-1 genomic RNA PBS. Selectivity in the incorporation of specific primer tRNALys,3 by HIV-1 may be due mainly to the identity of the PBS, rather than to specific viral protein-RNA interactions. These studies were supported by AMFAR, the American Foundation for AIDS Research.

DNA Primers HIV-1/*ENZYMOLOGY/GENETICS RNA-Directed DNA Polymerase/*METABOLISM RNA, Transfer, Lys/*METABOLISM Substrate Specificity Transcription, Genetic Viral Proteins/METABOLISM ABSTRACT