Department of Biochemistry and Molecular Biology, Oregon Health and Science University (OHSU), Portland, OR 97239, USA.
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77550-0620, USA. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550-0620, USA.
Science. 2015 Apr 24;348(6233):444-8. doi: 10.1126/science.aaa3974.
In cells, biosynthetic machinery coordinates protein synthesis and folding to optimize efficiency and minimize off-pathway outcomes. However, it has been difficult to delineate experimentally the mechanisms responsible. Using fluorescence resonance energy transfer, we studied cotranslational folding of the first nucleotide-binding domain from the cystic fibrosis transmembrane conductance regulator. During synthesis, folding occurred discretely via sequential compaction of N-terminal, α-helical, and α/β-core subdomains. Moreover, the timing of these events was critical; premature α-subdomain folding prevented subsequent core formation. This process was facilitated by modulating intrinsic folding propensity in three distinct ways: delaying α-subdomain compaction, facilitating β-strand intercalation, and optimizing translation kinetics via codon usage. Thus, de novo folding is translationally tuned by an integrated cellular response that shapes the cotranslational folding landscape at critical stages of synthesis.
在细胞中，生物合成机制协调蛋白质的合成和折叠，以优化效率并最小化偏离途径的结果。然而，用实验方法来描绘负责的机制一直很困难。我们使用荧光共振能量转移研究了囊性纤维化跨膜电导调节剂的第一个核苷酸结合域的共翻译折叠。在合成过程中，折叠通过 N 端、α-螺旋和α/β核心结构域的顺序紧缩离散地发生。此外，这些事件的时间至关重要；过早的α-亚结构域折叠会阻止随后的核心形成。通过三种不同的方式来促进这个过程：延迟α-亚结构域的紧缩，促进β-链的插入，以及通过密码子的使用优化翻译动力学。因此，从头折叠是由一种整合的细胞反应来调节的，这种反应在合成的关键阶段塑造了共翻译折叠的景观。
