title: A functional site of the GTPase-associated center within 28S ribosomal RNA probed with an anti-RNA autoantibody.
abstract: An anti-RNA autoantibody (anti-28S) was employed to identify structural and functional elements characteristic of a domain termed the 'GTPase center' in eukaryotic 28S ribosomal RNA. This antibody, an inhibitor of ribosome-associated GTP hydrolysis, has a unique property: it binds to the RNA domain of eukaryotes but not to that of prokaryotes. The antibody binding occurred in the presence of Mg2+ and protected from chemical modification three conserved bases (U1958, G1960 and A1990) and the base G1959 which is replaced by A in prokaryotic 23S rRNA (A1067 in Escherichia coli). In vitro substitution of G1959 to A drastically weakened the antibody binding, and the reciprocal substitution, A1067-->G of the E.coli domain conferred the binding ability. This suggests that the G base determines the specificity of antibody binding. The G1959 was also protected by the association of ribosomes with elongation factor EF-2. The result, together with protection of E.coli base A1067 by EFG [D.Moazed, I.M. Robertson and H.F. Noller (1988) Nature, 334, 362-364], suggests that the position of G1959 in eukaryotes and A1067 in prokaryotes constitutes at least part of the factor binding site irrespective of the base replacement during evolution.
authors.affiliation: Department of Biochemistry, Niigata University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Uchiumi
authors.forename: R
authors.initials: R
authors.lastname: Kominami
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D001323:Autoantibodies; D001483:Base Sequence; D004926:Escherichia coli / Q000276:immunology; D020558:GTP Phosphohydrolases / Q000276:immunology* / Q000378:metabolism; D006147:Guanine / Q000276:immunology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016337:RNA, Catalytic / Q000276:immunology* / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000276:immunology; D012339:RNA, Ribosomal, 28S / Q000276:immunology* / Q000378:metabolism; D051381:Rats
chemical_list: D001323:Autoantibodies; D016337:RNA, Catalytic; D012338:RNA, Ribosomal, 23S; D012339:RNA, Ribosomal, 28S; D006147:Guanine; D020558:GTP Phosphohydrolases