Roles of Pr55 gag and NCp7 in tRNA 3 Lys Genomic Placement and the Initiation Step of Reverse Transcription in Human Immunodeficiency Virus Type 1

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Abstract
To study in vivo tRNA3Lys genomic placement and the initiation step of reverse transcription in human immunodeficiency virus type 1, total viral RNA isolated from either wild-type or protease-negative (PR−) virus was used as the source of primer tRNA3Lys/genomic RNA templates in an in vitro reverse transcription assay. At low dCTP concentrations, both the rate and extent of the first nucleotide incorporated into tRNA3Lys, dCTP, were lower with PR− than with wild-type total viral RNA. Transient in vitro exposure of either type of primer/template RNA to NCp7 increased PR− dCTP incorporation to wild-type levels but did not change the level of wild-type dCTP incorporation. Exposure of either primer/template to Pr55gag had no effect on initiation. These results indicate that while Pr55gag is sufficient for tRNA3Lys placement onto the genome, exposure of this complex to mature NCp7 is required for optimum tRNA3Lys placement and initiation of reverse transcription.