title: Interaction of translation initiation factor eIF4B with the poliovirus internal ribosome entry site.
abstract: Poliovirus translation is initiated at the internal ribosome entry site (IRES). Most likely involving the action of standard initiation factors, this highly structured cis element in the 5" noncoding region of the viral RNA guides the ribosome to an internal silent AUG. The actual start codon for viral protein synthesis further downstream is then reached by ribosomal scanning. In this study we show that two of the secondary structure elements of the poliovirus IRES, domain V and, to a minor extent, domain VI, are the determinants for binding of the eukaryotic initiation factor eIF4B. Several mutations in domain V which are known to greatly affect poliovirus growth also seriously impair the binding of eIF4B. The interaction of eIF4B with the IRES is not dependent on the presence of the polypyrimidine tract-binding protein, which also binds to the poliovirus IRES. In contrast to its weak interaction with cellular mRNAs, eIF4B remains tightly associated with the poliovirus IRES during the 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. These results indicate that the interaction of eIF4B with the 3" region of the poliovirus IRES may be directly involved in translation initiation.
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, Friedrichstrasse 24, 35392 Giessen, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Ochs
authors.forename: Lanja
authors.initials: L
authors.lastname: Saleh
authors.forename: Gergis
authors.initials: G
authors.lastname: Bassili
authors.forename: Volker H
authors.initials: VH
authors.lastname: Sonntag
authors.forename: Amandus
authors.initials: A
authors.lastname: Zeller
authors.forename: Michael
authors.initials: M
authors.lastname: Niepmann
mesh_terms: D020121:5' Untranslated Regions; D000818:Animals; D001665:Binding Sites; D039642:Eukaryotic Initiation Factors; D006801:Humans; D051379:Mice; D009154:Mutation; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D017955:Poliovirus / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D038941:Polypyrimidine Tract-Binding Protein; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D011817:Rabbits; D012261:Ribonucleoproteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D020121:5' Untranslated Regions; D039642:Eukaryotic Initiation Factors; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D012269:Ribosomal Proteins; C031799:eIF-4B; C039913:ribosomal protein S80; D038941:Polypyrimidine Tract-Binding Protein