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Journal of Virology, September 1999, p. 7505-7514, Vol. 73, No. 9
Institute of Biochemistry, D-35392 Giessen,
Germany
Received 2 February 1999/Accepted 3 June 1999
Most eukaryotic initiation factors (eIFs) are required for internal
translation initiation at the internal ribosome entry site (IRES) of
picornaviruses. eIF4B is incorporated into ribosomal 48S initiation
complexes with the IRES RNA of foot-and-mouth disease virus (FMDV). In
contrast to the weak interaction of eIF4B with capped cellular mRNAs
and its release upon entry of the ribosomal 60S subunit, eIF4B remains
tightly associated with the FMDV IRES during formation of complete 80S
ribosomes. Binding of eIF4B to the IRES is energy dependent, and
binding of the small ribosomal subunit to the IRES requires the
previous energy-dependent association of initiation factors with the
IRES. The interaction of eIF4B with the IRES in 48S and 80S complexes
is independent of the location of the initiator AUG and thus
independent of the mechanism by which the small ribosomal subunit is
placed at the actual start codon, either by direct internal ribosomal
entry or by scanning. eIF4B does not greatly rearrange its binding to
the IRES upon entry of the ribosomal subunits, and the interaction of
eIF4B with the IRES is independent of the polypyrimidine tract-binding protein, which enhances FMDV translation.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Translation Initiation Factor eIF4B Interacts with a Picornavirus
Internal Ribosome Entry Site in both 48S and 80S Initiation Complexes
Independently of Initiator AUG Location
and
*
Corresponding author. Mailing address: Institute of
Biochemistry, Friedrichstrasse 24, D-35392 Giessen, Germany. Phone:
49-641-99-47421. Fax: 49-641-99-47429. E-mail:
michael.niepmann{at}biochemie.med.uni-giessen.de.
Present address: Institute of Medical Microbiology, University of
Basel, CH-4003 Basel, Switzerland.
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