Tunnel Formation Inferred from the I-Form Structures of the Proton-Driven Protein Secretion Motor SecDF
Tunnel Formation Inferred from the I-Form Structures of the Proton-Driven Protein Secretion Motor SecDF
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DOI：
10.1016/j.celrep.2017.04.030
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发表时间：
2017-05-02
期刊：
影响因子：
8.8
通讯作者：
Tsukazaki, Tomoya
中科院分区：
文献类型：
--
作者：
Furukawa, Arata;Yoshikaie, Kunihito;Tsukazaki, Tomoya
膜包埋的SecDF利用质子动力促进SecYEG转运子和SecA ATPase介导的蛋白质分泌。先前的结构研究表明，SecDF由12个能传导质子的跨膜螺旋和3个周质结构域组成，这些结构域至少形成两个特征过渡态，称为F和I型。我们报道了全长SecDF在圆分辨率2.6-到2.8-(A)时的I形式的结构。这些结构表明，I形式的SecDF可以产生一条穿透跨膜区的隧道，并作为受跨膜区保守的Asp残基调控的质子途径。在一种晶体结构中，周质腔与一种分子相互作用，可能是聚乙二醇，它可能模仿底物多肽。这项研究提供了对SEC蛋白易位的结构性见解，使未来的分析能够为SecDF开发更详细的工作模型。
Protein secretion mediated by SecYEG translocon and SecA ATPase is enhanced by membrane-embedded SecDF by using proton motive force. A previous structural study of SecDF indicated that it comprises 12 transmembrane helices that can conduct protons and three periplasmic domains, which form at least two characterized transition states, termed the F and I forms. We report the structures of full-length SecDF in I form at 2.6- to 2.8-(A) over circle resolution. The structures revealed that SecDF in I form can generate a tunnel that penetrates the transmembrane region and functions as a proton pathway regulated by a conserved Asp residue of the transmembrane region. In one crystal structure, periplasmic cavity interacts with a molecule, potentially polyethylene glycol, which may mimic a substrate peptide. This study provides structural insights into the Sec protein translocation that allows future analyses to develop a more detailed working model for SecDF.