Upstream sequences and cap proximity in the regulation of polyadenylation in ground squirrel hepatitis virus.

摘要: The polyadenylation signal of mammalian hepadnaviruses is unusual in that its hexanucleotide element the variant UAUAAA rather than AAUAAA. This functions inefficiently and must be augmented by multiple activator elements located upstream 400 nucleotides (nt) to promote efficient processing. Here we characterize one these elements, termed PS2, ground squirrel hepatitis virus. PS2 within 107 nt 5' raises efficiency this from < 10% 50 60%. It can function independently more conversely not required for their function. Its action orientation dependent, a predicted stem-loop structure necessary activity. sole maps terminal redundancy viral genomic RNA. Thus, it present, together with UAUAAA, at both 3' ends During RNA synthesis, poly(A) signals repeat are bypassed, while those copy used. ability other, activators suggests absence latter insufficient account bypass site, as had earlier proposed. Rather, short distance cap site end actively suppresses use, suppression experimentally relieved increasing 230 nt.