CIS-ELEMENTS AND TRANS-ACTING FACTORS REQUIRED FOR MINUS-STRAND DNA TRANSFER DURING REVERSE TRANSCRIPTION OF THE GENOMIC RNA OF MURINE LEUKEMIA-VIRUS

During reverse transcription of the retroviral genomic RNA, two obliga tory DNA strand transfers take place to synthesize the complete provir al DNA with two LTRs. We have previously shown that using an in vitro system made up of two viral RNAs mimicking the 5' and 3' regions of th e retroviral genome, both nucleocapsid protein and the repeat (R) sequ ences were necessary for minus strong-stop cDNA (ss-cDNA) transfer and elongation by reverse transcriptase (RT). In this payer we show that the basic residues of nucleocapsid protein NCp10 of Moloney murine leu kemia virus (MoMuLV), but not the zinc finger, are necessary for minus strand transfer. In order to examine the role of the R sequence repea ted at the 5' and 3' ends of the genome in minus strand DNA transfer, the MoMuLV R sequence of 68 nt was replaced by either HIV-1 R of 96 nt , or RSV R of 21 nt, or by an artificial sequence of 21 nt. Analysis o f MoMuLV DNA strand transfer from the 5' RNA to the 3' RNA and elongat ion in the presence of NCp10 and RT showed that it was high with contr ol MoMuLV R, high with RSV R, reduced with HIV-1 R, and undetectable w ith the artificial. R sequence. These results suggest that minus stran d DNA transfer is a process more complex than simple hybridization of ss-cDNA to the 3' R sequence of the genomic RNA. (C) 1998 Academic Pre ss Limited.