Structures of AAA protein translocase Bcs1 suggest translocation mechanism of a folded protein.,Nature Structural & Molecular Biology

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Structures of AAA protein translocase Bcs1 suggest translocation mechanism of a folded protein.
Nature Structural & Molecular Biology ( IF 12.5 ) Pub Date : 2020-02-10 , DOI: 10.1038/s41594-020-0373-0
Wai Kwan Tang _{1,

2} , Mario J Borgnia ₃ , Allen L Hsu ₃ , Lothar Esser ₁ , Tara Fox ₄ , Natalia de Val ₄ , Di Xia ₁

Affiliation

The mitochondrial membrane-bound AAA protein Bcs1 translocate substrates across the mitochondrial inner membrane without previous unfolding. One substrate of Bcs1 is the iron-sulfur protein (ISP), a subunit of the respiratory Complex III. How Bcs1 translocates ISP across the membrane is unknown. Here we report structures of mouse Bcs1 in two different conformations, representing three nucleotide states. The apo and ADP-bound structures reveal a homo-heptamer and show a large putative substrate-binding cavity accessible to the matrix space. ATP binding drives a contraction of the cavity by concerted motion of the ATPase domains, which could push substrate across the membrane. Our findings shed light on the potential mechanism of translocating folded proteins across a membrane, offer insights into the assembly process of Complex III and allow mapping of human disease-associated mutations onto the Bcs1 structure.

中文翻译：

AAA 蛋白转位酶 Bcs1 的结构表明折叠蛋白的转位机制。

线粒体膜结合的 AAA 蛋白 Bcs1 将底物转运穿过线粒体内膜，而无需事先展开。Bcs1 的一种底物是铁硫蛋白 (ISP)，它是呼吸复合物 III 的一个亚基。Bcs1 如何跨膜转运 ISP 尚不清楚。在这里，我们报告了两种不同构象的小鼠 Bcs1 结构，代表三种核苷酸状态。apo 和 ADP 结合结构揭示了同型七聚体，并显示出可进入基质空间的大的假定底物结合腔。ATP 结合通过 ATPase 结构域的协同运动驱动腔收缩，这可以推动底物穿过膜。我们的发现揭示了跨膜转运折叠蛋白的潜在机制，

更新日期：2020-02-10

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