Saccharomyces cerevisiae translation initiation factor Tif3 and its mammalian homologue, eIF-4B have RNA annealing activity

• Published in: The EMBO journal Vol. 14; no. 15; pp. 3820 - 3827
• Main Authors: Altmann, M, Wittmer, B, Methot, N, Sonenberg, N, Trachsel, H
• Format: Journal Article
• Language: English
• Published: England 01.08.1995
• Subjects: Animals; Base Sequence; binding; binding proteins; chemical reactions; Eukaryotic Initiation Factors; Fungal Proteins - genetics; Fungal Proteins - metabolism; Genes, Fungal - genetics; Histidine - genetics; messenger RNA; Models, Genetic; Molecular Sequence Data; Nucleic Acid Renaturation; Peptide Chain Initiation, Translational - genetics; Peptide Initiation Factors - genetics; Peptide Initiation Factors - metabolism; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - isolation & purification; ribosomes; Ribosomes - metabolism; RNA; RNA - metabolism; RNA Nucleotidyltransferases - genetics; RNA Nucleotidyltransferases - metabolism; RNA, Messenger - metabolism; RNA-binding proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins; Sequence Deletion; single stranded rna; translation
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1995.tb00051.x

The Saccharomyces cerevisiae TIF3 gene encodes the yeast homologue of mammalian translation initiation factor eIF-4B. We have added six histidine residues to the C-terminus of Tif3 protein (Tif3-His6p) and purified the tagged protein by affinity chromatography. Tif3-His6p stimulates translation and mRNA binding to ribosomes in a Tif3-dependent in vitro system. Furthermore, it binds to single-stranded RNA and catalyses the annealing of partially complementary RNA strands in vitro. In parallel experiments, RNA annealing activity could also be demonstrated for mammalian eIF-4B. A role for Tif3/eIF-4B and RNA annealing activity in the scanning process is proposed.