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J. Virol., 10 1996, 6803-6809, Vol 70, No. 10
S Perri and D Ganem
The terminal regions of hepatitis B virus (HBV) pregenomic RNA (pgRNA)
harbors sites governing many essential functions in the viral life cycle,
including polyadenylation, translation, RNA encapsidation, and DNA
synthesis. We have examined the binding of host proteins to a 170-
nucleotide region from the 5' end of HBV pgRNA; a large portion of this
region is duplicated at the 3' end of this terminally redundant RNA. By UV
cross-linking labeled RNA to HepG2 cell extracts, we have identified a
65-kDa factor (p65) of nuclear origin which can specifically bind to this
region. Two discrete binding sites were identified within this region; in
vitro cross-competition experiments suggest that the same factor binds to
both elements. One binding site (termed UBS) overlaps a portion of the
highly conserved stem-loop structure (epsilon), while the other site
(termed DBS) maps 35 nucleotides downstream of the hexanucleotide
polyadenylation sequence. Both binding sites are highly pyrimidine rich and
map to regions previously found to be important in the regulation of viral
polyadenylation. However, functional analysis of mutant binding sites in
vivo indicates that p65 is not involved in the polyadenylation of HBV
pgRNA. Potential roles for the factor in viral replication in vivo are
discussed.
Copyright © 1996, American Society for Microbiology
A host factor that binds near the termini of hepatitis B virus pregenomic RNA
Department of Microbiology, University of California, San Francisco 94143-0414, USA.
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