Translation initiation factor eIF4B interacts with a picornavirus internalribosome entry site in both 48S and 80S initiation complexes independentlyof initiator AUG location
K. Ochs et al., Translation initiation factor eIF4B interacts with a picornavirus internalribosome entry site in both 48S and 80S initiation complexes independentlyof initiator AUG location, J VIROLOGY, 73(9), 1999, pp. 7505-7514
Most eukaryotic initiation factors (eIFs) are required for internal transla
tion initiation at the internal ribosome entry site (IRES) of picornaviruse
s. eIF4B is incorporated into ribosomal 48S initiation complexes with the I
RES RNA of foot-and-mouth disease virus (FMDV). In contrast to the weak int
eraction of eIF4B with capped cellular mRNAs and its release upon entry of
the ribosomal 60S subunit, eIF4B remains tightly associated with the FMDV I
RES during formation of complete 80S ribosomes. Binding of eIF4B to the IRE
S is energy dependent, and binding of the small ribosomal subunit to the IR
ES requires the previous energy-dependent association of initiation factors
with the IRES. The interaction of eIF4B with the IRES in 48S and 80S compl
exes is independent of the location of the initiator AUG and thus independe
nt of the mechanism by which the small ribosomal subunit is placed at the a
ctual start codon, either by direct internal ribosomal entry or by scanning
, eIF4B does not greatly rearrange its binding to the IRES upon entry of th
e ribosomal subunits, and the interaction of eIF4B with the ISRES is indepe
ndent of the polypyrimidine tract-binding protein, which enhances FMDV tran
slation.