英国伦敦大学学院Christodoulou, John团队报道了核糖体稳定新生的多结构域蛋白的部分折叠中间体。相关研究成果于2022年8月4日发表在国际顶尖学术期刊《自然—化学》。

共翻译折叠对于确保生物活性蛋白质的生产至关重要。核糖体可以改变新生多肽链的折叠路径，但在实验上对其结构的理解仍然很难。

研究人员已经开发了新生链的位点特异性标记方法，以使用¹⁹F核磁共振（NMR）光谱检测和测量生物合成过程中，串联重复蛋白内免疫球蛋白样结构域访问的多个状态。通过检测在这种常见结构基序翻译过程中不同阶段捕获的核糖体，研究人员观察到两种先前未鉴定的中间体引起的高度展宽的NMR共振，它们稳定地分布在宽折叠转变中。利用分子动力学模拟并经低温电子显微镜证实，研究人员获得了这些部分折叠状态的模型，从而能够对核糖体结合位点进行实验验证，该位点有助于它们的高稳定性。

因此，研究人员证明了核糖体可以热力学调节折叠和其他共翻译过程的机制。大多数蛋白质必须在核糖体上进行共翻译折叠，以采用生物活性构象，但缺乏结构和机理描述。利用¹⁹F NMR光谱研究新生的多结构域蛋白质，现在已经鉴定出两种共翻译折叠中间体，它们比核糖体形成的中间体稳定得多，这表明核糖体可以热力学调节折叠。

附：英文原文

Title: The ribosome stabilizes partially folded intermediates of a nascent multi-domain protein

Author: Chan, Sammy H. S., Wodarski, Tomasz, Streit, Julian O., Cassaignau, Anas M. E., Woodburn, Lauren F., Ahn, Minkoo, Freiherr von Sass, Georg Johannes, Waudby, Christopher A., Budisa, Nediljko, Cabrita, Lisa D., Christodoulou, John

Issue&Volume: 2022-08-04

Abstract: Co-translational folding is crucial to ensure the production of biologically active proteins. The ribosome can alter the folding pathways of nascent polypeptide chains, yet a structural understanding remains largely inaccessible experimentally. We have developed site-specific labelling of nascent chains to detect and measure, using 19F nuclear magnetic resonance (NMR) spectroscopy, multiple states accessed by an immunoglobulin-like domain within a tandem repeat protein during biosynthesis. By examining ribosomes arrested at different stages during translation of this common structural motif, we observe highly broadened NMR resonances attributable to two previously unidentified intermediates, which are stably populated across a wide folding transition. Using molecular dynamics simulations and corroborated by cryo-electron microscopy, we obtain models of these partially folded states, enabling experimental verification of a ribosome-binding site that contributes to their high stabilities. We thus demonstrate a mechanism by which the ribosome could thermodynamically regulate folding and other co-translational processes. Most proteins must fold co-translationally on the ribosome to adopt biologically active conformations, yet structural, mechanistic descriptions are lacking. Using 19F NMR spectroscopy to study a nascent multi-domain protein has now enabled the identification of two co-translational folding intermediates that are significantly more stable than intermediates formed off the ribosome, suggesting that the ribosome may thermodynamically regulate folding.

DOI: 10.1038/s41557-022-01004-0

Source: https://www.nature.com/articles/s41557-022-01004-0