Force and velocity measured for single molecules of RNA polymerase
Force and velocity measured for single molecules of RNA polymerase
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DOI：
10.1126/science.282.5390.902
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发表时间：
1998-10-30
期刊：
影响因子：
56.9
通讯作者：
Block, SM
中科院分区：
文献类型：
--
作者：
Wang, MD;Schnitzer, MJ;Block, SM
RNA聚合酶（RNAP）在进行转录的同时沿DNA沿着移动，充当分子马达。大肠杆菌RNAP的单分子的转录速度进行了测量，作为逐步加大的力施加的反馈控制的光阱。RNAP力-速度曲线的形状与马达酶肌球蛋白或驱动蛋白的形状不同，表明在低负荷下限制转录速率的生化步骤不会产生运动。对数据库进行建模-高负载可能会通过促进结构变化来停止RNAP，该结构变化使全部或部分酶向后移动相对较大的距离，对应于5至10个碱基对。这与先前的模型形成对比，该模型假设力直接作用于单碱基易位步骤。
RNA polymerase (RNAP) moves along DNA while carrying out transcription, acting as a molecular motor. Transcriptional velocities for single molecules of Escherichia coli RNAP were measured as progressively larger forces were applied by;a feedback-controlled optical trap. The shapes of RNAP force-velocity curves are distinct from those of the motor enzymes myosin or kinesin, and indicate that biochemical steps limiting transcription rates at Low loads do not generate movement. Modeling the data suggests-that high Loads may halt RNAP by promoting a structural change which moves all or part of the enzyme backwards through a comparatively Large distance, corresponding to 5 to 10 base pairs. This contrasts with previous models that assumed force acts directly upon a single-base translocation step.