HDX-MS reveals nucleotide-regulated, anti-correlated opening and closure of SecA and SecY channels of the bacterial translocon
HDX-MS reveals nucleotide-regulated, anti-correlated opening and closure of SecA and SecY channels of the bacterial translocon
复制标题
HDX-MS 揭示细菌易位子 SecA 和 SecY 通道的核苷酸调节、反相关打开和关闭
DOI：
10.1101/595553
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Ahdash Z
中科院分区：
文献类型：
--
作者：
Ahdash Z
细菌Sec易位子是一种多蛋白复合物，负责在质膜上易位多种蛋白质。对于翻译后蛋白易位，sec通道SecYEG与马达蛋白SecA结合，介导atp依赖性的前蛋白跨膜转运。此前，已经提出了一种基于扩散的蛋白质分泌布朗棘轮机制；促进这一机制所需的结构动力学仍然未知。在这里，我们使用氢-氘交换质谱（HDX-MS）来揭示大肠杆菌Sec蛋白通道中惊人的核苷酸依赖性构象变化。除了先前报道的依赖于atp的SecA开放外，我们还观察到SecA在前蛋白周围的抑制和依赖于atp的收缩。ATP结合导致SecY打开，SecA关闭；而水解产生的ADP则具有相反的作用。这种交替行为可以帮助施加布朗棘轮的方向性，使蛋白质通过Sec机制运输。
The bacterial Sec translocon is a multi-protein complex responsible for translocating diverse proteins across the plasma membrane. For post-translational protein translocation, the Sec-channel – SecYEG – associates with the motor protein SecA to mediate the ATP-dependent transport of pre-proteins across the membrane. Previously, a diffusional-based Brownian ratchet mechanism for protein secretion has been proposed; the structural dynamics required to facilitate this mechanism remain unknown. Here, we employ hydrogen-deuterium exchange mass spectrometry (HDX-MS) to reveal striking nucleotide-dependent conformational changes in the Sec protein-channel fromEscherichia coli. In addition to the ATP-dependent opening of SecY, reported previously, we observe a counteracting, and ATP-dependent, constriction of SecA around the pre-protein. ATP binding causes SecY to open and SecA to close; while, ADP produced by hydrolysis, has the opposite effect. This alternating behaviour could help impose the directionality of the Brownian ratchet for protein transport through the Sec machinery.