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J. Virol., 05 1995, 2954-2961, Vol 69, No. 5
HH Roehl and BL Semler
To identify proteins involved in the formation of replication complexes at
the 3' end of poliovirus negative-strand RNA, a combined in vitro
biochemical and in vivo genetic approach was used. Five subgenomic cDNA
constructs were generated to transcribe different negative-strand RNA
fragments. In UV cross-linking assays, distinct differences in binding of
proteins in extracts from poliovirus-infected and uninfected cells to
virus-specific, radiolabeled transcripts were observed. Two proteins
present in extracts from poliovirus-infected cells with approximate
molecular masses of 36 and 38 kDa were shown to cross-link to the 3' end of
poliovirus negative-strand RNA. Appearance of the 36- and 38-kDa proteins
in UV cross-linking assays can be detected 3 to 3.5 h after infection, and
cross-linking reaches maximum levels by 5 h after infection. The binding
site for the 36-kDa protein overlaps with the computer-predicted loop b
region of stem-loop I, the so-called cloverleaf structure, and the RNA
sequence of this region is required for efficient binding. Transfection of
full-length, positive-sense RNA containing a five-nucleotide substitution
(positions 20 to 25) in the loop b region of stem-loop I into tissue
culture cells yielded only viral isolates with a reversion at position 24
(U-->C). This finding demonstrates that the wild-type cytidine residue
at position 24 is essential for virus replication. RNA binding studies with
transcripts corresponding to the 3' end of negative-strand RNA suggest that
complex formation with the 36-kDa protein plays an essential role during
the viral life cycle.
Copyright © 1995, American Society for Microbiology
Poliovirus infection enhances the formation of two ribonucleoprotein complexes at the 3' end of viral negative-strand RNA
Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine 92717, USA.
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