title: A six-domain structural model for Escherichia coli translation initiation factor IF2. Characterisation of twelve surface epitopes.
abstract: The Escherichia coli translation initiation factor IF2 is a 97 kDa protein which interacts with the initiator fMet-tRNAfMet, GTP and the ribosomal subunits during initiation of protein biosynthesis. For structural and functional investigations of the factor, we have raised and characterised monoclonal antibodies against E. coli IF2. Twelve epitopes have been localised at the surface of the protein molecule by three different methods: Interactions of the monoclonal antibodies with nested deletion mutants of IF2, comparison of the relative location of the epitopes in a competition immunoassay and cross-reactivity analyses of the monoclonal antibodies towards IF2 from Salmonella typhimurium, Klebsiella oxytoca, Enterobacter cloacae, Proteus vulgaris, and Bacillus stearothermophilus. These data are combined with predicted secondary structure and discussed in relation to a six-domain structural model for IF2. The model describes IF2 as a slightly elongated molecule with a structurally compact C-terminal domain, a well-conserved central GTP-binding domain, and a highly charged, solvent exposed N-terminal with protruding alpha-helical structures.
authors.affiliation: Institute of Molecular and Structural Biology, Aarhus University, Denmark.
authors.forename: K K
authors.initials: KK
authors.lastname: Mortensen
authors.forename: J
authors.initials: J
authors.lastname: Kildsgaard
authors.forename: J M
authors.initials: JM
authors.lastname: Moreno
authors.forename: S A
authors.initials: SA
authors.lastname: Steffensen
authors.forename: J
authors.initials: J
authors.lastname: Egebjerg
authors.forename: H U
authors.initials: HU
authors.lastname: Sperling-Petersen
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D001667:Binding, Competitive; D015153:Blotting, Western; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology; D004926:Escherichia coli / Q000737:chemistry* / Q000276:immunology; D006160:Guanosine Triphosphate / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D010448:Peptide Initiation Factors / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D039881:Prokaryotic Initiation Factor-2; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology; D017384:Sequence Deletion
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; D010448:Peptide Initiation Factors; D039881:Prokaryotic Initiation Factor-2; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate