title: Escherichia coli elongation factor G blocks stringent factor.
abstract: The relationship between the binding domains of elongation factor G(EF-G) and stringent factor (SF) on ribosomes was studied. The binding of highly purified, radioactively labeled, protein factors to ribosomes was monitored with a column system. The data show that binding of EF-G to ribosomes in the presence of fusidic acid and GDP or of the noncleavable analogue GDPCP prevents subsequent binding of SF to ribosomes. In addition, stabilization of the EF-G-ribosome complex by fusidic acid inhibits SF's enzymatic activities. Removal of protein L7/L12 from ribosomes leads to weaker binding of EF-G, while SF's binding and activity are unaffected. In the absence of L7/L12, EF-G-dependent inhibition of SF binding and function is reduced. The data presented in this report suggest that these two factors bind at overlapping, or at least interacting, ribosomal domains.
mesh_terms: D004926:Escherichia coli / Q000378:metabolism*; D001277:GTP Pyrophosphokinase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D006150:Guanine Nucleotides / Q000494:pharmacology; D006158:Guanosine Pentaphosphate / Q000494:pharmacology; D006159:Guanosine Tetraphosphate / Q000494:pharmacology; D007700:Kinetics; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors / Q000302:isolation & purification / Q000378:metabolism*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D006150:Guanine Nucleotides; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D006159:Guanosine Tetraphosphate; D006158:Guanosine Pentaphosphate; D010770:Phosphotransferases; D001277:GTP Pyrophosphokinase