大肠杆菌Tat转运酶的研究进展  

Progress in the studies on the Tat translocase in Escherichia coli

作　　者：张静[1] 张明[1] 

机构地区：[1]安徽农业大学生命科学学院,合肥230036

出　　处：《生物学杂志》2006年第6期1-3,共3页Journal of Biology

基　　金：安徽省高校"十五"优秀人才计划

摘　　要：TatA、TatB和TatC是大肠杆菌Tat转运酶的组成成分。研究表明各Tat蛋白具有不同的功能区域,TatA和TatB蛋白功能重要的位点位于N末端的穿膜片断、其后的双极性α-螺旋和铰链区。TatC的序列保守性低,N末端穿膜片断和位于胞质内的第一环区对转运是必需的。Tat转运酶各成分相互结合成复合物形式并相互依赖。TatA在细胞中高表达并自身聚合形成数量不等的同聚物,具有稳定TatBC复合物的作用,TatB有稳定TatC的功能,TatB和TatC两者结合形成二聚体。实验表明,TatA复合物形成转运通道,TatBC复合物通过TatC蛋白识别底物的信号肽并与底物结合,再在TatB介导下与TatA复合物结合形成具有活性的转运酶。Tat translocase consists of protein TatA,TatB and TatC in Escherichia coil.Resent studies have shown that these Tat proteins would form two kinds of complex,one is TatABC and another is homo-oligomeric complex TatA.The Tat proteins and their different domains have different effects on the translocation.A membrane-spanning α-helix at the amino terminus and an amphipathic helix of TatA and TatB have great effect on the proteins translocation in contrast with N-termianl region.As for TatC,the N-terminal region and the first cytoplasmic loop are essential for protein export.In addition,the components of Tat translocase have some dependent relative and different function in the course of translocation.TatA would be stable for the complex TatBC,so is TatB for TatC.Moreover,TatA is expressed at higher level than TatB and TatC and can aggregate to be homo-oligomeric complex so TatA maybe form different size translocation channels with different amount oligomeric complexes.TatC can recognize the twin arginine signal peptide of substrates and bind with substrates and with the TarA by the aid of TatB complex to complete the thranslocation,so TatBC complexes maybe take a role to control the open and close of the cannels.

关 键 词：大肠杆菌 Tat蛋白质转运系统 Tat转运酶 Tat蛋白质 

分 类 号：Q502[生物学—生物化学]