Conformational transition of Sec machinery inferred from bacterial SecYE structures.
Conformational transition of Sec machinery inferred from bacterial SecYE structures.
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DOI：
10.1038/nature07421
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发表时间：
2008-10-16
期刊：
影响因子：
64.8
通讯作者：
Nureki, Osamu
中科院分区：
文献类型：
--
作者：
Tsukazaki, Tomoya;Mori, Hiroyuki;Fukai, Shuya;Ishitani, Ryuichiro;Mori, Takaharu;Dohmae, Naoshi;Perederina, Anna;Sugita, Yuji;Vassylyev, Dmitry G.;Ito, Koreaki;Nureki, Osamu
超过30%的蛋白质被分泌穿过或整合到膜中。它们的新合成形式含有可切割的信号序列或不可切割的膜锚序列，其将它们引导至进化上保守的Sec易位子（原核生物中的SecYEG和真核生物中的Sec 61，包括α-、γ-和β-亚基）。然后，易位子作为蛋白质传导通道发挥作用。这些蛋白质定位过程发生在翻译时或翻译后。在细菌中，SecA ATP酶驱动翻译后易位。迄今为止，唯一可用的高分辨率的易位子结构是来自詹氏甲烷球菌的SecYEβ，它缺乏SecA。在这里，我们提出了3.2-X-分辨率晶体结构的SecYE易位子从SecA含有生物体，嗜热栖热菌。该结构被解析为与抗SecY Fab片段的复合物，揭示了SecYE的“预开放”状态，与之前的SecYEβ结构相比，其中几个跨膜螺旋发生了位移，以产生一个疏水性裂缝。向细胞质开放。Fab和SecA结合至SecY的胞质结构域的尖端处的共同位点。分子动力学和二硫化物映射分析表明，预开放状态可能代表SecA结合诱导的SecYE构象转变。此外，我们确定了一个SecA-SecYE接口，其中包括SecA残基最初埋在蛋白质内，表明通道和电机组件的Sec机械进行合作的构象变化的功能复合物的形成。
Over 30% of proteins are secreted across or integrated into membranes. Their newly synthesized forms contain either cleavable signal sequences or non-cleavable membrane anchor sequences, which direct them to the evolutionarily conserved Sec translocon (SecYEG in prokaryotes and Sec61, comprising α-, γ- and β-subunits, in eukaryotes). The translocon then functions as a protein-conducting channel. These processes of protein localization occur either at or after translation. In bacteria, the SecA ATPase drives post-translational translocation. The only high-resolution structure of a translocon available so far is that for SecYEβ from the archaeon Methanococcus jannaschii, which lacks SecA. Here we present the 3.2-Å-resolution crystal structure of the SecYE translocon from a SecA-containing organism, Thermus thermophilus. The structure, solved as a complex with an anti-SecY Fab fragment, revealed a ‘pre-open’ state of SecYE, in which several transmembrane helices are shifted, as compared to the previous SecYEβ structure, to create a hydrophobic crack open to the cytoplasm. Fab and SecA bind to a common site at the tip of the cytoplasmic domain of SecY. Molecular dynamics and disulphide mapping analyses suggest that the pre-open state might represent a SecYE conformational transition that is inducible by SecA binding. Moreover, we identified a SecA–SecYE interface that comprises SecA residues originally buried inside the protein, indicating that both the channel and the motor components of the Sec machinery undergo cooperative conformational changes on formation of the functional complex.
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DOI：
10.1083/jcb.200412019
发表时间：
2005-04-25
期刊：
The Journal of cell biology
影响因子：
--
作者：
Cannon KS;Or E;Clemons WM Jr;Shibata Y;Rapoport TA
通讯作者：
Rapoport TA
影响因子：
64.5
作者：
ECONOMOU, A;WICKNER, W
通讯作者：
WICKNER, W
影响因子：
4.1
作者：
Kalé, L;Skeel, R;Schulten, K
通讯作者：
Schulten, K
影响因子：
64.8
作者：
Mitra, K;Schaffitzel, C;Frank, J
通讯作者：
Frank, J
影响因子：
3.2
作者：
Mori, H;Ito, K
通讯作者：
Ito, K