Nucleotide sequence analysis of squirrel monkey retrovirus reveals a novel primer-binding site for tRNALys1,2

Nucleotide sequences of a DNA fragment containing the long terminal repeat (LTR) of squirrel monkey retrovirus (SMRV) were determined. Sequence analysis showed that the SMRV LTR is 456 base pairs (bp) long and is bounded by 2-bp inverted repeats. Within the U3 region, there are two 43-bp repeats and two 42-bp repeats which are homologous to each other. These repeats are likely to provide enhancer activities commonly observed in other enhancer sequences. Following the repeats are transcriptional regulatory sequences including a CAT box, a Goldberg-Hogness box, and a polyadenylation signal, all positioned within the U3 region of SMRV LTR. A 22-nucleotide sequence immediately downstream from the LTR was found to be complementary to tRNALys1,2, suggesting that tRNALys1,2 serves as the primer for the reverse transcription of SMRV viral RNA.