title: A single-headed dimer of Escherichia coli ribosomal protein L7/L12 supports protein synthesis.
abstract: During protein synthesis, the two elongation factors Tu and G alternately bind to the 50S ribosomal subunit at a site of which the protein L7/L12 is an essential component. L7/L12 is present in each 50S subunit in four copies organized as two dimers. Each dimer consists of distinct domains: a single N-terminal ("tail") domain that is responsible for both dimerization and binding to the ribosome via interaction with the protein L10 and two independent globular C-terminal domains ("heads") that are required for binding of elongation factors to ribosomes. The two heads are connected by flexible hinge sequences to the N-terminal domain. Important questions concerning the mechanism by which L7/L12 interacts with elongation factors are posed by us in response to the presence of two dimers, two heads per dimer, and their dynamic, mobile properties. In an attempt to answer these questions, we constructed a single-headed dimer of L7/L12 by using recombinant DNA techniques and chemical cross-linking. This chimeric molecule was added to inactive core particles lacking wild-type L7/L12 and shown to restore activity to a level approaching that of wild-type two-headed L7/L12.
authors.affiliation: Department of Pediatrics, School of Medicine, University of California, Davis, CA 95616, USA. avoleinikov@ucdavis.edu
authors.forename: A V
authors.initials: AV
authors.lastname: Oleinikov
authors.forename: G G
authors.initials: GG
authors.lastname: Jokhadze
authors.forename: R R
authors.initials: RR
authors.lastname: Traut
mesh_terms: D019281:Dimerization; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D014644:Genetic Variation; D007700:Kinetics; D008958:Models, Molecular; D020653:Peptide Elongation Factor G; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D010445:Peptide Elongation Factors / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D014508:Urea / Q000494:pharmacology
chemical_list: D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; D014508:Urea; D004228:Dithionitrobenzoic Acid; D010444:Peptide Elongation Factor Tu