Large-scale simulations of ribosomal decoding

核糖体解码的大规模模拟

• 批准号: 7277970
• 负责人: Karissa Y Sanbonmatsu
• 金额: $ 2.97万
• 依托单位: LOS ALAMOS NAT SECTY-LOS ALAMOS NAT LAB
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7277970
• 关键词: aminoglycoside antibiotics; biochemistry; computer simulation; conformation; hydrogen bond; molecular dynamics; mutant; nucleic acid sequence; ribosomes; transfer RNA

DESCRIPTION (provided by applicant): The ribosome implements the genetic code by translating information residing in nucleic acid into protein, a process which lies at the heart of all organisms. Within the translational cycle, the decoding step distinguishes the ribosome from other molecular machines. During this step, the ribosome must discriminate between correct and incorrect transfer RNAs, accepting only those whose amino acid corresponds to the messenger RNA codon, as prescribed by the genetic code. Recent x-ray structural data has unveiled the local and global conformational changes involved in correct transfer RNA recognition by the ribosome; however, the order of events and cause-effect relation between local and global changes is not clear. We will use large-scale all-atom molecular dynamics simulations, validated by biochemical and x-ray data, to study the relation between local decoding interactions and large-scale conformational changes of the small ribosomal subunit. In particular, (1) We will use large-scale computer simulations to investigate the relative importance of codon-anticodon-ribosome hydrogen bonds at the decoding center on the open-to-closed conformational change of the small ribosomal subunit. Predictions based on these simulations will be tested biochemically. (2) We will use replica exchange molecular dynamics to investigate the flipping out of the decoding bases, A1492-A1493, from small subunit helix 44 in the presence of cognate tRNA, near-cognate tRNA, aminoglycoside antibiotics and resistance mutants. We will again compare with antibiotic-oligo binding. (3) We will investigate the order of events during tRNA recognition, in atomic detail, by testing whether the above base-flipping induces the open-to-closed conformational change of the small ribosomal subunit, with and without, decoding antibiotics. As alternative strategies, We will (1) improve sampling by using a mesoscale model, which couples small scale simulations of the decoding center, to information obtained from large scale simulations, (2) Perform all-atom normal mode calculations to study the effect of decoding base flipping and antibiotics on the overall motion of the ribosome, and (3) Attempt to modify force field potentials, by slightly modifying the delta gamma and epsilon torsional parameter coefficients. Our simulations will serve as a template for other researchers to perform million atom simulations. We will directly address the issues of time scale limitations, kinetic trapping and force field accuracy, with enhanced sampling simulation techniques and iteration between experimental data and simulation.

描述（由申请人提供）：核糖体通过将核酸中的信息翻译成蛋白质来实现遗传密码，这是所有生物体的核心过程。在翻译循环中，解码步骤将核糖体与其他分子机器区分开来。在这个步骤中，核糖体必须区分正确和不正确的转移RNA，只接受那些其氨基酸对应于信使RNA密码子的RNA，如遗传密码所规定的。最近的X射线结构数据揭示了核糖体正确识别转移RNA所涉及的局部和全局构象变化;然而，事件的顺序以及局部和全局变化之间的因果关系尚不清楚。我们将使用大规模的全原子分子动力学模拟，生物化学和X射线数据验证，研究本地解码相互作用和大规模的核糖体小亚基的构象变化之间的关系。特别是，（1）我们将使用大规模的计算机模拟来研究密码子-反密码子-核糖体氢键在核糖体小亚基的开放到闭合构象变化的解码中心的相对重要性。基于这些模拟的预测将进行生物化学测试。(2)我们将使用复制交换分子动力学研究翻转的解码碱基，A1492-A1493，从小亚基螺旋44在同源tRNA，近同源tRNA，氨基糖苷类抗生素和耐药突变体的存在下。我们将再次与寡核苷酸结合进行比较。(3)我们将研究tRNA识别过程中的事件顺序，在原子细节，通过测试是否上述碱基翻转诱导小核糖体亚基的开放到封闭的构象变化，有和没有，解码抗生素。作为替代策略，我们将（1）通过使用中尺度模型来改进采样，该模型将解码中心的小尺度模拟与从大尺度模拟获得的信息相耦合，（2）执行全原子正常模式计算以研究解码碱基翻转和抗生素对核糖体整体运动的影响，以及（3）尝试修改力场势，通过稍微修改Δ γ和Δ γ扭转参数系数。我们的模拟将作为其他研究人员进行百万原子模拟的模板。我们将直接解决时间尺度限制，动力学捕获和力场精度的问题，增强采样模拟技术和实验数据和模拟之间的迭代。