Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Ribosomes position their substrate at stereochemistry suitable for peptide bond formation, and promote substrate-mediated cata-lysis. The linkage between substrate orientation, dominated by remote interactions, and a sizable symmetrical region identified in all known ribosome structures indicates a guided rotatory motion of aminoacylated-tRNAs along a ribosomal path leadings to the advance of nascent peptides into the protein exit tunnel at an extended conformation. | Abstract P1 - FEBS Datta Plenary Lectureship Award P1-001 Peptide bond formation cotranslational folding and antibiotics synergism A. Yonath Structural Biology Weizmann Inst. Rehovot Israel. E-mail ada.yonath@weizmann.ac.il Ribosomes position their substrate at stereochemistry suitable for peptide bond formation and promote substrate-mediated catalysis. The linkage between substrate orientation dominated by remote interactions and a sizable symmetrical region identified in all known ribosome structures indicates a guided rotatory motion of aminoacylated-tRNAs along a ribosomal path leadings to the advance of nascent peptides into the protein exit tunnel at an extended conformation. The symmetry related region can transfer intra-ribosomal signals between remote locations since it connects all ribosomal functionally sites. These included the decoding and peptide-bond-formation sites the protein exit tunnel the tRNA entrance and exit environments and the protein exit tunnel entrance. The symmetry relates RNA backbone and nucleotides orientation but not sequence homology. Thus suggesting that ribosomes evolved by gene-fusion and demonstrates the superiority of the functional requirements over sequence conservation. The protein exit tunnel acts as a dynamic functional entity capable of taking part in nascent protein elongation discrimination arrest and partial protein folding. Initial steps in chaperon-aided cotranslational folding are associated with significant mobility of both the bacterial trigger factor and a ribosomal protein at the tunnel opening. Similarly major conformational alterations induced by ribosomal recycling factor play a key role in the termination steps of protein biosyntheses. Comparative analysis of antibiotics binding modes to a eubacterial pathogen model and an archaeal sharing properties with eukaryotes showed that despite the overall conservation of the ribosome phylogenetic and conformational variations in antibiotics binding pocket allow .
