title: The interplay of mRNA stimulatory signals required for AUU-mediated initiation and programmed -1 ribosomal frameshifting in decoding of transposable element IS911.
abstract: The IS911 bacterial transposable element uses -1 programmed translational frameshifting to generate the protein required for its mobility: translation initiated in one gene (orfA) shifts to the -1 frame and continues in a second overlapping gene (orfB), thus generating the OrfAB transposase. The A-AAA-AAG frameshift site of IS911 is flanked by two stimulatory elements, an upstream Shine-Dalgarno sequence and a downstream stem-loop. We show here that, while they can act independently, these stimulators have a synergistic effect when combined. Mutagenic analyses revealed features of the complex stem-loop that make it a low-efficiency stimulator. They also revealed the dual role of the upstream Shine-Dalgarno sequence as (i) a stimulator of frameshifting, by itself more potent than the stem-loop, and (ii) a mandatory determinant of initiation of OrfB protein synthesis on an AUU codon directly preceding the A6G motif. Both roles rely on transient base pairing of the Shine-Dalgarno sequence with the 3' end of 16S rRNA. Because of its effect on frameshifting, the Shine-Dalgarno sequence is an important determinant of the level of transposase in IS911-containing cells, and hence of the frequency of transposition.
authors.affiliation: Laboratoire de Microbiologie et Génétique Moléculaire, UMR5100, Centre National de la Recherche Scientifique, Université Paul Sabatier-Toulouse III, 118 Route de Narbonne, Toulouse, 31062 Cedex, France.
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Prère
authors.forename: Isabelle
authors.initials: I
authors.lastname: Canal
authors.forename: Norma M
authors.initials: NM
authors.lastname: Wills
authors.forename: John F
authors.initials: JF
authors.lastname: Atkins
authors.forename: Olivier
authors.initials: O
authors.lastname: Fayet
mesh_terms: D001665:Binding Sites; D004251:DNA Transposable Elements; D018965:Frameshifting, Ribosomal; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D019895:Transposases / Q000096:biosynthesis
chemical_list: D004251:DNA Transposable Elements; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D019895:Transposases