Deckert Annika, Waudby Christopher A, Wlodarski Tomasz, Wentink Anne S, Wang Xiaolin, Kirkpatrick John P, Paton Jack F S, Camilloni Carlo, Kukic Predrag, Dobson Christopher M, Vendruscolo Michele, Cabrita Lisa D, Christodoulou John
Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom; Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, United Kingdom;
Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
Proc Natl Acad Sci U S A. 2016 May 3;113(18):5012-7. doi: 10.1073/pnas.1519124113. Epub 2016 Apr 18.
The ribosome is increasingly becoming recognized as a key hub for integrating quality control processes associated with protein biosynthesis and cotranslational folding (CTF). The molecular mechanisms by which these processes take place, however, remain largely unknown, in particular in the case of intrinsically disordered proteins (IDPs). To address this question, we studied at a residue-specific level the structure and dynamics of ribosome-nascent chain complexes (RNCs) of α-synuclein (αSyn), an IDP associated with Parkinson's disease (PD). Using solution-state nuclear magnetic resonance (NMR) spectroscopy and coarse-grained molecular dynamics (MD) simulations, we find that, although the nascent chain (NC) has a highly disordered conformation, its N-terminal region shows resonance broadening consistent with interactions involving specific regions of the ribosome surface. We also investigated the effects of the ribosome-associated molecular chaperone trigger factor (TF) on αSyn structure and dynamics using resonance broadening to define a footprint of the TF-RNC interactions. We have used these data to construct structural models that suggest specific ways by which emerging NCs can interact with the biosynthesis and quality control machinery.
核糖体日益被认为是整合与蛋白质生物合成和共翻译折叠（CTF）相关的质量控制过程的关键枢纽。然而，这些过程发生的分子机制在很大程度上仍然未知，特别是对于内在无序蛋白（IDP）而言。为了解决这个问题，我们在残基特异性水平上研究了与帕金森病（PD）相关的IDPα-突触核蛋白（αSyn）的核糖体-新生链复合物（RNC）的结构和动力学。使用溶液态核磁共振（NMR）光谱和粗粒度分子动力学（MD）模拟，我们发现，尽管新生链（NC）具有高度无序的构象，但其N端区域显示出共振加宽，这与涉及核糖体表面特定区域的相互作用一致。我们还使用共振加宽来定义触发因子（TF）-RNC相互作用的足迹，研究了核糖体相关分子伴侣触发因子（TF）对αSyn结构和动力学的影响。我们利用这些数据构建了结构模型，这些模型提出了新生NC与生物合成和质量控制机制相互作用的具体方式。
