title: Functional interactions between the G' subdomain of bacterial translation factor EF-G and ribosomal protein L7/L12.
abstract: Protein L7/L12 of the bacterial ribosome plays an important role in activating the GTP hydrolytic activity of elongation factor G (EF-G), which promotes ribosomal translocation during protein synthesis. Previously, we cross-linked L7/L12 from two residues (209 and 231) flanking alpha-helix AG' in the G' subdomain of Escherichia coli EF-G. Here we report kinetic studies on the functional effects of mutating three neighboring glutamic acid residues (224, 228, and 231) to lysine, either singly or in combination. Two single mutations (E224K and E228K), both within helix AG', caused large defects in GTP hydrolysis and smaller defects in ribosomal translocation. Removal of L7/L12 from the ribosome strongly reduced the activities of wild type EF-G but had no effect on the activities of the E224K and E228K mutants. Together, these results provide evidence for functionally important interactions between helix AG' of EF-G and L7/L12 of the ribosome.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Roxana
authors.initials: R
authors.lastname: Nechifor
authors.forename: Marat
authors.initials: M
authors.lastname: Murataliev
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Wilson
mesh_terms: D019943:Amino Acid Substitution; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D020125:Mutation, Missense; D020653:Peptide Elongation Factor G / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000502:physiology*; D017433:Protein Structure, Secondary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D020653:Peptide Elongation Factor G; D012269:Ribosomal Proteins; C512844:rplL protein, E coli; D006160:Guanosine Triphosphate