A tweezers-like motion of the ATP-binding cassette dimer in an ABC transport cycle
A tweezers-like motion of the ATP-binding cassette dimer in an ABC transport cycle
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DOI：
10.1016/j.molcel.2003.08.004
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发表时间：
2003-09-01
期刊：
影响因子：
16
通讯作者：
Quiocho, FA
中科院分区：
文献类型：
--
作者：
Chen, J;Lu, G;Quiocho, FA
ATP结合盒（ABC）转运蛋白的ATP酶组分通过结合和水解ATP为转运蛋白提供动力。三种不同的二聚体构型中，来自大肠杆菌的麦芽糖转运蛋白的ATP酶亚基MalK的晶体结构揭示了ATP酶的主要构象变化。虽然其他核苷酸结合结构域或亚基在不存在跨膜区段的情况下彼此显示低亲和力，但MalK二聚体通过另外的C-末端结构域的相互作用而稳定。在两个无核苷酸结构中，N-末端核苷酸结合结构域以不同程度分离，并且通过C-末端调节结构域的接触维持二聚体。在ATP结合形式中，核苷酸结合结构域接触，两个ATP沿着二聚体界面隐藏。二聚体的两个核苷酸结合结构域像镊子一样打开和关闭，表明ATP酶活性的调节机制可能与易位紧密耦合。
The ATPase components of ATP binding cassette (ABC) transporters power the transporters by binding and hydrolyzing ATP. Major conformational changes of an ATPase are revealed by crystal structures of MalK, the ATPase subunit of the maltose transporter from Escherichia coli, in three different dimeric configurations. While other nucleotide binding domains or subunits display low affinity for each other in the absence of the transmembrane segments, the MalK dimer is stabilized through interactions of the additional C-terminal domains. In the two nucleotide-free structures, the N-terminal nucleotide binding domains are separated to differing degrees, and the dimer is maintained through contacts of the C-terminal regulatory domains. In the ATP-bound form, the nucleotide binding domains make contact and two ATPs lie buried along the dimer interface. The two nucleotide binding domains of the dimer open and close like a pair of tweezers, suggesting a regulatory mechanism for ATPase activity that may be tightly coupled to translocation.