Baram David, Yonath Ada
Department of Structural Biology, The Weizmann Institute, 76100 Rehovot, Israel.
FEBS Lett. 2005 Feb 7;579(4):948-54. doi: 10.1016/j.febslet.2004.11.063.
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.
核糖体是发挥底物定位作用并促进底物介导催化的核酶。肽键在一个对称区域内形成，因此表明核糖体是通过基因融合进化而来的。远程相互作用在适合肽键形成的立体化学中主导底物定位，精细的结构设计通过旋转运动引导反应的持续性。新生蛋白质以伸展构象被导向出口通道，以适应通道狭窄的入口。通道动力学促进其在延伸、识别、细胞信号传导以及新生蛋白质运输到伴侣辅助折叠位点过程中的相互作用。核糖体循环因子诱导的构象改变促进亚基解离。值得注意的是，尽管抗生素的识别由一个也参与耐药性的单核苷酸的身份决定，但其他核苷酸决定抗生素的有效性。
