Mobility of Cytoplasmic, Membrane, and DNA-Binding Proteins in Escherichia coli
Mobility of Cytoplasmic, Membrane, and DNA-Binding Proteins in Escherichia coli
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DOI：
10.1016/j.bpj.2009.11.002
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发表时间：
2010-02-17
影响因子：
3.4
通讯作者：
Sourjik, Victor
中科院分区：
文献类型：
--
作者：
Kumar, Mohit;Mommer, Mario S.;Sourjik, Victor
蛋白质的迁移率影响大多数细胞过程，如酶反应、信号转导和大分子复合体的组装尽管如此重要，但关于蛋白质在细菌细胞内扩散的系统信息很少。本文将光漂白后的荧光恢复与数值模拟相结合，分析了一组荧光蛋白质融合在细菌细胞质、质膜和类核中的迁移性，估计细胞质和膜蛋白质的扩散系数严重依赖于跨膜螺旋的大小和数量，因此蛋白质在两个隔室中的扩散明显被一系列障碍所阻碍，产生所谓的分子筛选效应。然而，这些阻碍网络本身似乎是动态的，并允许大的蛋白质和复合体缓慢且几乎不依赖于大小的运动。所获得的蛋白质迁移率对分子质量和跨膜螺旋数目的依赖关系可以作为预测蛋白质在大肠杆菌中扩散速度的参考。DNA结合蛋白质的迁移率显然主要取决于它们的结合专一性，高度特异性的TetR阻遏物的FRAP恢复动力学慢于相对非特异性的H-NS调节子
Protein mobility affects most cellular processes, such as the rates of enzymatic reactions, signal transduction, and assembly of macromolecular complexes Despite such importance, little systematic information is available about protein diffusion inside bacterial cells Here we combined fluorescence recovery after photobleaching with numerical modeling to analyze mobility of a set of fluorescent protein fusions in the bacterial cytoplasm, the plasma membrane, and in the nucleoid Estimated diffusion coefficients of cytoplasmic and membrane proteins show steep dependence on the size and on the number of transmembrane helices, respectively Protein diffusion in both compartments is thus apparently obstructed by a network of obstacles, creating the so-called molecular sieving effect. These obstructing networks themselves, however, appear to be dynamic and allow a slow and nearly size-independent movement of large proteins and complexes The obtained dependencies of protein mobility on the molecular mass and the number of transmembrane helices can be used as a reference to predict diffusion rates of proteins in Escherichia colt Mobility of DNA-binding proteins apparently mainly depends on their binding specificity, with FRAP recovery kinetics being slower for the highly specific TetR repressor than for the relatively nonspecific H-NS regulator