Moving folded proteins across the bacterial cell membrane
Moving folded proteins across the bacterial cell membrane
复制标题
DOI：
10.1099/mic.0.25900-0
复制
发表时间：
2003-03-01
期刊：
影响因子：
2.8
通讯作者：
Berks, BC
中科院分区：
文献类型：
--
作者：
Palmer, T;Berks, BC
TAT蛋白输出系统位于细菌细胞质膜上，与已知的SEC途径平行运行。虽然SEC系统只运输非结构化底物，但TAT途径的功能是运输折叠蛋白。因此，TAT转位酶面临着一项艰巨的挑战，即在不使膜对质子和其他离子自由渗透的情况下，在细菌细胞质膜上移动结构化的大分子底物。TAT途径的底物通常是与细胞质中的辅因子分子结合的蛋白质，因此在出口之前被折叠。这种含有周质辅因子的蛋白质对大多数类型的细菌呼吸和光合作用能量代谢都是必不可少的。此外，TAT途径还参与外膜生物合成和细菌致病。底物通过含有连续的、基本不变的精氨酸残基的氨基末端信号序列靶向TAT途径，蛋白质在TAT系统中的运动通过跨膜质子电化学梯度提供能量。TATA蛋白可能形成转运通道，而TatBC蛋白则作为识别底物蛋白信号肽的受体复合体。
The Tat protein export system is located in the bacterial cytoplasmic membrane and operates in parallel to the well-known Sec pathway. While the Sec system only transports unstructured substrates, the function of the Tat pathway is to translocate folded proteins. The Tat translocase thus faces the formidable challenge of moving structured macromolecular substrates across the bacterial cytoplasmic membrane without rendering the membrane freely permeable to protons and other ions. The substrates of the Tat pathway are often proteins that bind cofactor molecules in the cytoplasm, and are thus folded, prior to export. Such periplasmic cofactor-containing proteins are essential for most types of bacterial respiratory and photosynthetic energy metabolism. In addition, the Tat pathway is involved in outer membrane biosynthesis and in bacterial pathogenesis. Substrates are targeted to the Tat pathway by amino-terminal signal sequences harbouring consecutive, essentially invariant, arginine residues, and movement of proteins through the Tat system is energized by the transmembrane proton electrochemical gradient. The TatA protein probably forms the transport channel while the TatBC proteins act as a receptor complex that recognizes the signal peptide of the substrate protein.