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. 2002 Jul 1;99(14):9515–9520. doi: 10.1073/pnas.142123199

Figure 1.

Figure 1

Reverse transcription of viral RNA. (i) Minus-strand DNA synthesis is initiated from a tRNALys-3 primer (gray arrow) annealed to the pbs. (ii) The U5 and R regions of the viral RNA (thin line) are copied into DNA (thick line), and the RNase H activity of RT degrades the viral RNA (the dotted line represents degraded RNA). (iii) Minus-strand DNA can be transferred to the 3′ end of the viral RNA because of the complementarity of the viral RNA R region and the minus-strand DNA. (iv) Minus-strand DNA elongation copies the RNA genome, and the RNase H activity of RT degrades the viral RNA. The ppt is resistant to RNase H cleavage and serves as the primer for plus-strand DNA synthesis. Two specific cleavages by RNase H generate the ppt primer (arrowheads). (v) Plus-strand DNA synthesis is initiated from the ppt and copies the U3, R, and U5 regions of the minus-strand DNA. RNase H removes the tRNA primer 1 base from the RNA/DNA junction and the ppt at the RNA/DNA junction (arrowheads). (vi) Plus-strand transfer occurs using the complementarity of the pbs and the ends of the viral DNA. Extension of the plus- and minus-strands complete the synthesis of the viral DNA. The ribonucleotide (rA) at the 5′ end of the minus strand is derived from the tRNA. HIV-1 RT removes the tRNA one base from the RNA-DNA junction (15–18); other retroviral RTs remove the entire tRNA (2). (vii) The structure of full-length viral DNA.