The Saccharomyces cerevisiae translation initiation factor Tif3 and its mammalian homologue, eIF-4B, have RNA annealing activity.
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.
Altmann
M
M
Institute of Biochemistry and Molecular Biology, University of Berne, Switzerland.
Wittmer
B
B
Méthot
N
N
Sonenberg
N
N
Trachsel
H
H
D000818:Animals; D001483:Base Sequence; D039642:Eukaryotic Initiation Factors; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal / Q000235:genetics; D006639:Histidine / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009695:Nucleic Acid Renaturation; D010442:Peptide Chain Initiation, Translational / Q000235:genetics*; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion
D039642:Eukaryotic Initiation Factors; D005656:Fungal Proteins; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C083432:TIF3 protein, S cerevisiae; C031799:eIF-4B; D006639:Histidine; D012313:RNA; D012316:RNA Nucleotidyltransferases