Turner Raymond J, Papish Andriyka L, Sargent Frank
Department of Biological Sciences, University of Calgary, Alberta, Canada.
Can J Microbiol. 2004 Apr;50(4):225-38. doi: 10.1139/w03-117.
The twin-arginine protein transport (Tat) system is a remarkable molecular machine dedicated to the translocation of fully folded proteins across energy-transducing membranes. Complex cofactor-containing Tat substrates acquire their cofactors prior to export, and substrate proteins actually require to be folded before transport can proceed. Thus, it is very likely that mechanisms exist to prevent wasteful export of immature Tat substrates or to curb competition between immature and mature substrates for the transporter. Here we assess the primary sequence relationships between the accessory proteins implicated in this process during assembly of key respiratory enzymes in the model prokaryote Escherichia coli. For each respiratory enzyme studied, a redox enzyme maturation protein (REMP) was assigned. The main finding from this review was the hitherto unexpected link between the Tat-linked REMP DmsD and the nitrate reductase biosynthetic protein NarJ. The evolutionary link between Tat transport and cofactor insertion processes is discussed.
双精氨酸蛋白转运（Tat）系统是一种非凡的分子机器，致力于将完全折叠的蛋白质转运穿过能量转换膜。含有复杂辅因子的Tat底物在输出之前获得其辅因子，并且底物蛋白实际上需要在运输能够进行之前折叠。因此，很可能存在防止未成熟Tat底物的浪费性输出或抑制未成熟和成熟底物之间对转运体的竞争的机制。在这里，我们评估了在模式原核生物大肠杆菌中关键呼吸酶组装过程中涉及此过程的辅助蛋白之间的一级序列关系。对于所研究的每种呼吸酶，都指定了一种氧化还原酶成熟蛋白（REMP）。这篇综述的主要发现是迄今为止Tat相关的REMP DmsD与硝酸还原酶生物合成蛋白NarJ之间意外的联系。讨论了Tat转运与辅因子插入过程之间的进化联系。
