Twin-Arginine-Dependent Translocation of SufI in the Absence of Cytosolic Helper Proteins
Twin-Arginine-Dependent Translocation of SufI in the Absence of Cytosolic Helper Proteins
复制标题
DOI：
10.1021/bi900520d
复制
发表时间：
2009-06-16
期刊：
影响因子：
2.9
通讯作者：
Muller, Matthias
中科院分区：
文献类型：
--
作者：
Holzapfel, Eva;Moser, Michael;Muller, Matthias
细菌和类囊体膜中存在的双精氨酸转位(TAT)机制能够运输完全折叠的蛋白质。一些TAT前体蛋白的折叠需要专门的伴侣，在成熟过程中还需要隔离信号序列。目前尚不清楚信号序列结合的伴侣蛋白是否是所有TAT底物蛋白的普遍先决条件。在这里，我们研究了大肠杆菌TAT信号序列与普通伴侣和肽基-脯氨酰-顺式、反式异构酶相互作用的倾向。位点特异性光交联显示FK506结合蛋白具有明显的特异性。然而，在没有胞质伴侣的情况下，TAT底物SuFI被转移到大肠杆菌倒置的内膜囊泡中。我们的结果表明，在大肠杆菌中，胞液伴侣对于双精氨酸依赖的无辅因子底物的输出并不是必不可少的。
The twin-arginine translocation (Tat) machinery present in bacterial and thylakoidal membranes is able to transport fully folded proteins. Folding of some Tat precursor proteins requires dedicated chaperones that also sequester the signal sequence during the maturation process. Whether or not signal sequence-binding chaperones are a general prerequisite for all Tat substrate proteins is not known. Here, we have studied the propensity of Tat signal sequences of Escherichia coli to interact with general chaperones and peptidyl-prolyl-cis, trans-isomerases. Site-specific photocross-linking revealed clear specificity for FK506-binding proteins. Nevertheless transport of the Tat substrate SufI into inverted inner membrane vesicles of E. coli was found to occur in the bona fide, absence of any cytosolic chaperone. Our results suggest that in E. coli, cytosolic chaperones are not essential for the twin-arginine-dependent export of cofactor-less substrates.