枯草芽孢杆菌双精氨酸转运系统TatAy 蛋白的溶液结构

存在于细菌和植物叶绿体中的双精氨酸(Tat)蛋白质转运系统能将底物蛋白以折叠的状态进行跨膜转运．该系统中的单次跨膜膜蛋白TatA 通过自身寡聚形成转运
底物蛋白的通道．该文应用液体核磁共振方法解析了枯草芽孢杆菌TatAy 蛋白在十二烷基胆碱磷酸胶束中的结构，它是由一个跨膜螺旋(TMH)和一个两亲性螺旋(APH)构成的L 型结构．通过与已经报道的枯草芽孢杆菌TatAd 蛋白的结构比较，该文能够鉴定出参与维持L 型构象的重要氨基酸残基，并指出了TatA 蛋白家族中若干较为保守的结构特征．在此基础上，该文讨论了保守残基在TatA 通道形成过程中可能发挥的作用．

Solution Structure ofBacillus subtilis Twin-Arginine Translocation TatAy Protein

The twin-arginine transport (Tat) systems in bacteria and plant chloroplasts translocate cargo proteins across cellular membranes in their folded states. The single-pass transmembrane protein TatA forms the protein translocation channel via self-oligomerization. Herein, we present the structure ofBacillus subtilis TatAy protein in dodecylphosphocholine micelles determined by solution NMR method. TatAy adopts an L-shaped conformation formed by a transmembrane helix (TMH) and an amphipathic helix (APH). Structural comparison of TatAy protein with the previously reportedB. subtilis TatAd protein highlights essential residues at the hinge region for maintaining the L-shaped conformation, and suggests a few conserved structural features for the TatA protein family. Possible roles for the conserved residues in the TatA channel formation are discussed.