title: Competition and cooperation amongst yeast elongation factors.
abstract: Elongation factor 3 (EF-3) is an essential requirement for translation in fungi. We previously reported activation of EF-3-ATPase by yeast ribosomes. EF-3 interacts with both ribosomal subunits and shows high affinity for 60S subparticles. Translational inhibitors alpha-sarcin, ricin and auto-immune antibodies to GTPase-activation center inhibit binding of EF-2 but not of EF-3 to yeast ribosomes. EF-2 competes with EF-3 for the ribosomal binding sites and inhibits EF-3-ATPase activity. Neomycin relieves the inhibitory effect of EF-2 on EF-3 function. The apparent competition between EF-2 and EF-3 may represent binding of these two proteins to specific conformational states of the ribosome. EF-3 stimulates ternary complex binding to yeast ribosomes. Neither the binding of EF-3 to ribosomes, nor the ribosome-dependent EF-3-ATPase activity are influenced by EF-1 alpha. Three lines of experimental evidence suggest a direct interaction between EF-1 alpha and EF-3. A polyclonal antibody to EF-3 immunoprecipitates EF-1 alpha along with EF-3. EF-1 alpha co-migrates with GST-EF-3 on glutathione-Sepharose columns. ELISA tests demonstrate an interference of EF-3/anti-EF-3 interaction by EF-1 alpha but not by EF-2. These results strongly suggest that the stimulatory effect of EF-3 on the ternary complex binding to yeast ribosomes involves a direct interaction between EF-1 alpha and EF-3.
authors.affiliation: Department of Biochemistry, Medical College of Wisconsin, Milwaukee 53226, USA.
authors.forename: O
authors.initials: O
authors.lastname: Kovalchuke
authors.forename: R
authors.initials: R
authors.lastname: Kambampati
authors.forename: E
authors.initials: E
authors.lastname: Pladies
authors.forename: K
authors.initials: K
authors.lastname: Chakraburtty
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001667:Binding, Competitive; D005656:Fungal Proteins / Q000502:physiology*; D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins