title: Translational operator of mRNA on the ribosome: how repressor proteins exclude ribosome binding.
abstract: The ribosome of Thermus thermophilus was cocrystallized with initiator transfer RNA (tRNA) and a structured messenger RNA (mRNA) carrying a translational operator. The path of the mRNA was defined at 5.5 angstroms resolution by comparing it with either the crystal structure of the same ribosomal complex lacking mRNA or with an unstructured mRNA. A precise ribosomal environment positions the operator stem-loop structure perpendicular to the surface of the ribosome on the platform of the 30S subunit. The binding of the operator and of the initiator tRNA occurs on the ribosome with an unoccupied tRNA exit site, which is expected for an initiation complex. The positioning of the regulatory domain of the operator relative to the ribosome elucidates the molecular mechanism by which the bound repressor switches off translation. Our data suggest a general way in which mRNA control elements must be placed on the ribosome to perform their regulatory task.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.
authors.forename: Lasse
authors.initials: L
authors.lastname: Jenner
authors.forename: Pascale
authors.initials: P
authors.lastname: Romby
authors.forename: Bernard
authors.initials: B
authors.lastname: Rees
authors.forename: Clemens
authors.initials: C
authors.lastname: Schulze-Briese
authors.forename: Mathias
authors.initials: M
authors.lastname: Springer
authors.forename: Chantal
authors.initials: C
authors.lastname: Ehresmann
authors.forename: Bernard
authors.initials: B
authors.lastname: Ehresmann
authors.forename: Dino
authors.initials: D
authors.lastname: Moras
authors.forename: Gulnara
authors.initials: G
authors.lastname: Yusupova
authors.forename: Marat
authors.initials: M
authors.lastname: Yusupov
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D020029:Base Pairing; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000737:chemistry / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D012097:Repressor Proteins / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D016963:Thermus thermophilus / Q000235:genetics / Q000378:metabolism*; D013914:Threonine-tRNA Ligase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D012358:RNA, Transfer, Met; D038621:Regulatory Sequences, Ribonucleic Acid; D012097:Repressor Proteins; D012269:Ribosomal Proteins; D013914:Threonine-tRNA Ligase