Folding pathway of an Ig domain is conserved on and off the ribosome.
Folding pathway of an Ig domain is conserved on and off the ribosome.
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DOI：
10.1073/pnas.1810523115
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发表时间：
2018-11-27
影响因子：
11.1
通讯作者：
Best RB
中科院分区：
文献类型：
--
作者：
Tian P;Steward A;Kudva R;Su T;Shilling PJ;Nickson AA;Hollins JJ;Beckmann R;von Heijne G;Clarke J;Best RB
大多数蛋白质需要折叠成特定的 3D 结构才能发挥作用。分离蛋白质的折叠机制已通过实验和理论进行了深入研究。然而，在细胞中，蛋白质不会单独折叠，而是在翻译过程中由核糖体合成为线性链。因此，很自然地要问蛋白质在合成过程中的哪个点折叠，以及这是否与分离的蛋白质分子的折叠不同。通过研究一个已明确表征的蛋白质结构域肌联蛋白 I27（在翻译过程中在不同点停滞）的折叠，我们发现它已经在核糖体出口通道的口中折叠，并且其机制几乎与分离的蛋白质相同。由于核糖体占据的体积，共翻译折叠的蛋白质可能在有限的构型空间中进行折叠。这种环境与核糖体的紧密结合如何影响蛋白质的折叠途径？先前的研究表明，许多蛋白质（包括小的单结构域）的共翻译折叠过程直接受到核糖体的影响。在这里，我们研究了全β Ig结构域titin I27的共翻译折叠。使用基于阻滞肽的测定和冷冻电镜的结构研究，我们表明 I27 在核糖体出口通道的口中折叠。使用动力学模型来模拟逃脱逮捕的力依赖性，准确地预测折叠蛋白质的分数作为长度的函数。我们使用这些模拟来探测核糖体内外的折叠途径。我们的模拟（也重现了 I27 突变形式的实验）表明，I27 折叠，同时仍然隔离在核糖体出口通道的口中，其途径与游离 I27 基本相同，只是关键接触从 C 末端到 N 末端发生了微妙的变化。
Most proteins need to fold into a specific 3D structure to function. The mechanism by which isolated proteins fold has been thoroughly studied by experiment and theory. However, in the cell proteins do not fold in isolation but are synthesized as linear chains by the ribosome during translation. It is therefore natural to ask at which point during synthesis proteins fold, and whether this differs from the folding of isolated protein molecules. By studying folding of a well-characterized protein domain, titin I27, stalled at different points during translation, we show that it already folds in the mouth of the ribosome exit tunnel and that the mechanism is almost identical to that of the isolated protein. Proteins that fold cotranslationally may do so in a restricted configurational space, due to the volume occupied by the ribosome. How does this environment, coupled with the close proximity of the ribosome, affect the folding pathway of a protein? Previous studies have shown that the cotranslational folding process for many proteins, including small, single domains, is directly affected by the ribosome. Here, we investigate the cotranslational folding of an all-β Ig domain, titin I27. Using an arrest peptide-based assay and structural studies by cryo-EM, we show that I27 folds in the mouth of the ribosome exit tunnel. Simulations that use a kinetic model for the force dependence of escape from arrest accurately predict the fraction of folded protein as a function of length. We used these simulations to probe the folding pathway on and off the ribosome. Our simulations—which also reproduce experiments on mutant forms of I27—show that I27 folds, while still sequestered in the mouth of the ribosome exit tunnel, by essentially the same pathway as free I27, with only subtle shifts of critical contacts from the C to the N terminus.
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影响因子：
16.8
作者：
Cabrita LD;Cassaignau AME;Launay HMM;Waudby CA;Wlodarski T;Camilloni C;Karyadi ME;Robertson AL;Wang X;Wentink AS;Goodsell L;Woolhead CA;Vendruscolo M;Dobson CM;Christodoulou J
通讯作者：
Christodoulou J
影响因子：
15
作者：
Chen, Hu;Yuan, Guohua;Winardhi, Ricksen S.;Yao, Mingxi;Popa, Ionel;Fernandez, Julio M.;Yan, Jie
通讯作者：
Yan, Jie
DOI：
10.1073/pnas.1812756115
发表时间：
2018-10-02
影响因子：
11.1
作者：
Farias-Rico, Jose Arcadio;Selin, Frida Ruud;von Heijne, Gunnar
通讯作者：
von Heijne, Gunnar
影响因子：
64.8
作者：
Ferbitz, L;Maier, T;Ban, N
通讯作者：
Ban, N
影响因子：
1.6
作者：
Evans, MS;Clark, TF;Clark, PL
通讯作者：
Clark, PL