Viral small nuclear ribonucleoproteins bind a protein implicated in messenger RNA destabilization.

Abstract Herpesvirus saimiri (HVS) is one of several primate viruses that carry genes for small RNAs. The five H. saimiri-encoded U RNAs ( HSURs) are the most abundant viral transcripts expressed in transformed marmosetT lymphocytes. They assemble with host proteins common to spliceosomal small nuclear ribonucleoproteins( snRNPs). HSURs1, 2, and 5 exhibit sequences at their 5' ends identical to the AUUUA motif, which targets a number of protooncogene, cytokine, and lymphokinemRNAs for rapid degradation. We show that a 32-kDa protein previously demonstrated to bind to the 3' untranslated regionof several unstable messages can be UV crosslinked specifically to HSUR1, 2, and 5 transcripts in vitro, as well as to endogenous HSUR snRNPs. Our results suggest an unusual role for these viral snRNPs: HSURsmay function to attenuate the rapid degradation of certain cellular mRNAs, thereby facilitating viral transformationof host T lymphocytes.