title: Functional interaction of yeast elongation factor 3 with yeast ribosomes.
abstract: Elongation factor 3 (EF-3) is a unique and essential requirement of the fungal translational apparatus. EF-3 is a monomeric protein with a molecular mass of 116,000. EF-3 is required by yeast ribosomes for in vitro translation and for in vivo growth. The protein stimulates the binding of EF-1 alpha :GTP:aa-tRNA ternary complex to the ribosomal A-site by facilitating release of deacylated-tRNA from the E-site. The reaction requires ATP hydrolysis. EF-3 contains two ATP-binding sequence motifs (NBS). NBSI is sufficient for the intrinsic ATPase function. NBSII is essential for ribosome-stimulated activity. By limited proteolysis, EF-3 was divided into two distinct functional domains. The N-terminal domain lacking the highly charged lysine blocks failed to bind ribosomes and was inactive in the ribosome-stimulated ATPase activity. The C-terminally derived lysine-rich fragment showed strong binding to yeast ribosomes. The purported S5 homology region of EF-3 at the N-terminal end has been reported to interact with 18S ribosomal RNA. We postulate that EF-3 contacts rRNA and/or protein(s) through the C-terminal end. Removal of these residues severely weakens its interaction mediated possibly through the N-terminal domain of the protein.
authors.affiliation: Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226, USA. chakra@mcw.edu
authors.forename: K
authors.initials: K
authors.lastname: Chakraburtty
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015003:Yeasts / Q000235:genetics* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D010445:Peptide Elongation Factors; D029701:Saccharomyces cerevisiae Proteins; C111584:YEF3 protein, S cerevisiae; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases