title: From peptide-bond formation to cotranslational folding: dynamic, regulatory and evolutionary aspects.
abstract: Ribosomes are ribozymes exerting substrate positioning and promoting substrate-mediated catalysis. Peptide-bonds are formed within a symmetrical region, thus suggesting that ribosomes evolved by gene-fusion. Remote interactions dominate substrate positioning at stereochemistry suitable for peptide-bond formation and elaborate architectural-design guides the processivity of the reaction by rotatory motion. Nascent proteins are directed into the exit tunnel at extended conformation, complying with the tunnel's narrow entrance. Tunnel dynamics facilitate its interactive participation in elongation, discrimination, cellular signaling and nascent-protein trafficking into the chaperon-aided folding site. Conformational alterations, induced by ribosomal-recycling factor, facilitate subunit dissociation. Remarkably, although antibiotics discrimination is determined by the identity of a single nucleotide, involved also in resistance, additional nucleotides dictate antibiotics effectiveness.
authors.affiliation: Department of Structural Biology, The Weizmann Institute, 76100 Rehovot, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Baram
authors.forename: Ada
authors.initials: A
authors.lastname: Yonath
mesh_terms: D019143:Evolution, Molecular; D015394:Molecular Structure; D010441:Peptide Chain Elongation, Translational; D010458:Peptidyl Transferases / Q000737:chemistry* / Q000502:physiology; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017510:Protein Folding; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000502:physiology
chemical_list: D012343:RNA, Transfer; D010458:Peptidyl Transferases