title: Identification in a pseudoknot of a U.G motif essential for the regulation of the expression of ribosomal protein S15.
abstract: The ribosomal protein S15 from Escherichia coli binds to a pseudoknot in its own messenger. This interaction is an essential step in the mechanism of S15 translational autoregulation. In a previous study, a recognition determinant for S15 autoregulation, involving a U.G wobble pair, was located in the center of stem I of the pseudoknot. In this study, an extensive mutagenesis analysis has been conducted in and around this U.G pair by comparing the effects of these mutations on the expression level of S15. The results show that the U.G wobble pair cannot be substituted by A.G, C.A, A.C, G.U, or C.G without loss of the autocontrol. In addition, the base pair C.G, adjacent to the 5' side of U, cannot be flipped or changed to another complementary base pair without also inducing derepression of translation. A unique motif, made of only two adjacent base pairs, U.G/C.G, is essential for S15 autoregulation and is presumably involved in direct recognition by the S15 protein.
authors.affiliation: Unité de Propre de Recherche 9073 du Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Bénard
authors.forename: N
authors.initials: N
authors.lastname: Mathy
authors.forename: M
authors.initials: M
authors.lastname: Grunberg-Manago
authors.forename: B
authors.initials: B
authors.lastname: Ehresmann
authors.forename: C
authors.initials: C
authors.lastname: Ehresmann
authors.forename: C
authors.initials: C
authors.lastname: Portier
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006147:Guanine; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry; D012269:Ribosomal Proteins / Q000096:biosynthesis* / Q000737:chemistry; D014498:Uracil; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C036004:ribosomal protein S15; D014498:Uracil; D006147:Guanine; D001616:beta-Galactosidase