CHARACTERIZATION OF RIBONUCLEOPROTEIN COMPLEXES CONTAINING AN ABUNDANT POLYADENYLATED NUCLEAR-RNA ENCODED BY KAPOSIS SARCOMA-ASSOCIATED HERPESVIRUS (HUMAN HERPESVIRUS-8)

Infection with Kaposi's sarcoma-associated herpesvirus (KSHV) (also ca lled human herpesvirus 8) is strongly linked to all forms of Kaposi's sarcoma. We have previously identified two polyadenylated KSHV transcr ipts that are actively transcribed in Kaposi's sarcoma (KS) tumors and in KSHV-infected B-lymphoma cells. One of these RNAs (termed T1.1 or nut-1 RNA) is a 1.1-kb transcript present in a subpopulation of KS tum or cells. This RNA is localized to the nucleus of infected cells and h as no open reading frames longer than 62 codons, suggesting that it ma y not function as an mRNA in vivo. Here we demonstrate that nut-1 RNA is a lytic-cycle gene product that is found in high-molecular-weight r ibonucleoprotein complexes in infected cell nuclei. The transcript lac ks the trimethylguanosine (TMG) cap found in many U-like small nuclear RNAs, but a subpopulation of nut-1 RNAs can associate with Sm protein -containing small nuclear ribonucleoproteins, as judged by immunopreci pitation analyses using monoclonal anti-Sm and anti-TMG antibodies. Th is interaction does not require other viral gene products, and deletio n of the sole candidate Sm binding site on nut-1 RNA does not ablate t his association. This finding suggests an indirect interaction with Sm -containing structures, and models for such associations are presented .