Cabrita Lisa D, Cassaignau AnaÏs M E, Launay Helene M M, Waudby Christopher A, Wlodarski Tomasz, Camilloni Carlo, Karyadi Maria-Evangelia, Robertson Amy L, Wang Xiaolin, Wentink Anne S, Goodsell Luke, Woolhead Cheryl A, Vendruscolo Michele, Dobson Christopher M, Christodoulou John
institute of Structural and Molecular Biology, University College London.
School of Crystallography, Birkbeck College, University of London, London, United Kingdom.
Nat Struct Mol Biol. 2016 Apr;23(4):278-285. doi: 10.1038/nsmb.3182. Epub 2016 Feb 29.
Although detailed pictures of ribosome structures are emerging, little is known about the structural and cotranslational folding properties of nascent polypeptide chains at the atomic level. Here we used solution-state NMR spectroscopy to define a structural ensemble of a ribosome-nascent chain complex (RNC) formed during protein biosynthesis in Escherichia coli, in which a pair of immunoglobulin-like domains adopts a folded N-terminal domain (FLN5) and a disordered but compact C-terminal domain (FLN6). To study how FLN5 acquires its native structure cotranslationally, we progressively shortened the RNC constructs. We found that the ribosome modulates the folding process, because the complete sequence of FLN5 emerged well beyond the tunnel before acquiring native structure, whereas FLN5 in isolation folded spontaneously, even when truncated. This finding suggests that regulating structure acquisition during biosynthesis can reduce the probability of misfolding, particularly of homologous domains.
尽管核糖体结构的详细图片不断涌现，但在原子水平上，对于新生多肽链的结构和共翻译折叠特性仍知之甚少。在此，我们使用溶液态核磁共振光谱来定义大肠杆菌蛋白质生物合成过程中形成的核糖体-新生链复合物（RNC）的结构集合，其中一对免疫球蛋白样结构域呈现出一个折叠的N端结构域（FLN5）和一个无序但紧密的C端结构域（FLN6）。为了研究FLN5如何在共翻译过程中获得其天然结构，我们逐步缩短了RNC构建体。我们发现核糖体调节折叠过程，因为FLN5的完整序列在获得天然结构之前远远超出了通道，而单独的FLN5即使被截断也能自发折叠。这一发现表明，在生物合成过程中调节结构获得可以降低错误折叠的概率，尤其是同源结构域的错误折叠概率。
