Quaternary Structure and Functional Unit of Energy Coupling Factor (ECF)-type Transporters
Quaternary Structure and Functional Unit of Energy Coupling Factor (ECF)-type Transporters
复制标题
DOI：
10.1074/jbc.m110.199224
复制
发表时间：
2011-02-18
影响因子：
4.8
通讯作者：
Slotboom, Dirk Jan
中科院分区：
文献类型：
--
作者：
ter Beek, Josy;Duurkens, Ria H.;Slotboom, Dirk Jan
ATP 结合盒 (ABC) 转运蛋白介导多种底物跨膜转运。我们确定了最近发现的ECF型（能量耦合因子）ABC转运蛋白的四级结构和功能单元，该转运蛋白在原核生物中广泛存在。 ECF 转运蛋白是由保守的供能模块（两个外周 ATP 酶和整合膜蛋白 EcfT）和负责底物特异性的非保守整合膜蛋白（S 成分）组成的蛋白质复合物。不同底物的 S 成分在氨基酸序列上通常不相关，但可能与相同的供能模块相关。在这里，乳酸乳球菌的能量模块被证明可以与生物体中发现的八种预测的 S 成分中的每一种形成稳定的复合物。通过光散射测定了其中三个配合物的四级结构。 EcfT、两种 ATP 酶（EcfA 和 EcfA`）以及 S 成分以 1:1:1:1 的比例存在。这些复合物在脂蛋白体中重建，并显示出介导 ATP 依赖性运输。 ECF 型转运蛋白是已知最小的 ABC 转运蛋白。
ATP-binding cassette (ABC) transporters mediate transport of diverse substrates across membranes. We have determined the quaternary structure and functional unit of the recently discovered ECF-type (energy coupling factor) of ABC transporters, which is widespread among prokaryotes. ECF transporters are protein complexes consisting of a conserved energizing module (two peripheral ATPases and the integral membrane protein EcfT) and a non-conserved integral membrane protein responsible for substrate specificity (S-component). S-components for different substrates are often unrelated in amino acid sequence but may associate with the same energizing module. Here, the energizing module from Lactococcus lactis was shown to form stable complexes with each of the eight predicted S-components found in the organism. The quaternary structures of three of these complexes were determined by light scattering. EcfT, the two ATPases (EcfA and EcfA`), and the S-components were found to be present in a 1:1:1:1 ratio. The complexes were reconstituted in proteoliposomes and shown to mediate ATP-dependent transport. ECF-type transporters are the smallest known ABC transporters.