title: [Mutational analysis of the functional role of the loop region in the elongation factor G fourth domain in the ribosomal translocation].
abstract: Seven variants of Thermus thermophilus elongation factor G (EF-G) with mutations in loops of domain IV were constructed by PCR. Point mutations Arg504-->Thr, Pro554-->Thr, or Ile534-->Asp did not affect the GTPase and translocational activities of EF-G. Similar results were obtained for mutants with tetra- or hexapeptide inserts in two loops located at the tip and two loops at the base of domain IV. Insertion of tetrapeptide Gly-Ser-Gly-Thr into loop 501--504 at the tip of domain IV dramatically reduced the activity of EF-G in poly(U)-directed polyphenylalanine synthesis on ribosomes, and halved its translocational activity. The intact conformation of loop Thr501-Gly-Gly-Arg504 was assumed to be essential for sterically perfect, efficient interaction of EF-G with the ribosome. The structural and biochemical data on the 30S subunit and EF-G were analyzed to specify the position of EF-G relative to the 30S and 50S ribosomal subunits.
authors.affiliation: Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Kolesnikov
authors.forename: A T
authors.initials: AT
authors.lastname: Gudkov
mesh_terms: D004252:DNA Mutational Analysis; D006160:Guanosine Triphosphate / Q000378:metabolism; D020653:Peptide Elongation Factor G / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D017354:Point Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012270:Ribosomes / Q000378:metabolism*; D016963:Thermus thermophilus / Q000235:genetics
chemical_list: D020653:Peptide Elongation Factor G; D010455:Peptides; C012001:polyphenylalanine; D006160:Guanosine Triphosphate