A FUNCTIONAL INTERACTION BETWEEN REV AND YEAST PRE-MESSENGER-RNA IS RELATED TO SPLICING COMPLEX-FORMATION

The HIV-1 Rev protein regulates viral gene expression by enhancing the export of partially spliced or nonspliced viral transcripts to the cy toplasm. This activity is mediated by the interaction of Rev with a hi ghly structured viral RNA sequence, the Rev response element (RRE). In this paper, Rev regulation has been recapitulated in the yeast Saccha romyces cerevisiae. The data show that Rev enhances yeast pre-mRNA tra nslation in an RRE-dependent manner and requires intact RNA binding an d effector domains. In addition, reporter gene mutations in the 5' spl ice site and in the branch point are epistatic to and eliminate Rev re sponsiveness, i.e. some spliceosome assembly pathway steps precede a f unctional interaction with Rev. The results indicate that some of the Rev-interacting components are conserved between yeast and mammals and suggest that Rev acts on yeast pre-mRNA in the context of the spliceo some.