A common mRNA 3?-end processing in the baculoviridae family?.

PILLOFF, M.G.; LOZANO, M.E.; GHIRINGHELLI, P.D.

Bariloche

Congreso; XXXIX Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2003

It is known that the correct processing of the 3´-end of cellular mRNA precursors depends on several proteins and binding elements. CPSF binds an A-rich positioning element (optimally AAUAAA), situated 10 to 30 nt. upstream of the cleavage site and is required for cleavage of the mRNA precursor as well as for polyadenylation. Another factor, CstF binds a downstream less sequence-specific U-rich element, designated downstream element, located 10 to 20 nt. downstream of cleavage site and increases the specificity of binding. Following cleavage, CPSF and polyA-polymerase are required for an efficient polyadenylation. On the other hand, the baculoviral RNA polymerase required different sequence elements for the 3?-end mRNA processing of late and very late viral genes, principally a cluster of Us (at least four). However, it can not be discarded that an A-rich region (including the canonical polyadenylation signal) plays a role of positioning element for the viral RNA polymerase. GP64 is a viral gene transcribed early and late after infection. We determined the nucleotide sequence of the 3?-end of early gp64 baculoviral mRNAs which are transcribed by the cellular RNA polymerase and determined the site for cleavage and polyadenylation. Furthermore we analysed the 3´-end sequences for other baculoviral genes and propose a flexible pattern of sequence elements for the 3?-end-processing of early bavuloviral mRNAs.