HIV-1 REVERSE TRANSCRIPTION - A TERMINATION STEP AT THE CENTER OF THEGENOME

During HIV-1 reverse transcription, the plus-strand of viral DNA is sy nthesized as two discrete segments. me show here that synthesis of the upstream segment terminates at the center of the genome after an 88 o r 98 nucleotide strand displacement of the downstream segment, initiat ed at the central polypurine tract. Thus, the final structure of unint egrated linear HIV-1 DNA includes a central plus-strand overlap. In vi tro reconstitution using only purified reverse transcriptase with appr opriate DNA hybrids gas e rise to efficient and accurate termination, which was dramatically amplified in the context of strand displacement . Mutation of the sequence immediately upstream of the termination sit es almost completely abolished termination both in infected cells and in vitro. This mutation profoundly impaired replication of HIV-1. We c onclude that proper central plus-strand termination, mediated by a nov el cis-active termination sequence, is a key step in HIV-1 replication .