Giglione Carmela, Fieulaine Sonia, Meinnel Thierry
Centre National de la Recherche Scientifique, Protein Maturation and Cell Fate, Institut des Sciences du Végétal, Bât.23A, 1 avenue de la Terrasse, F-91198 Gif-sur-Yvette cedex, France.
Trends Biochem Sci. 2009 Aug;34(8):417-26. doi: 10.1016/j.tibs.2009.04.003. Epub 2009 Jul 31.
Recent major advances have been made in understanding how cotranslational events are achieved in the course of protein biosynthesis. Specifically, several studies have shed light into the dynamic process of how nascent chains emerging from the ribosome are supported by protein biogenesis factors to ensure both processing and folding mechanisms. To take into account the awareness that coordination is needed, a new 'concerted model' recently proposed simultaneous action of both processes on the ribosome. In the model, any emerging nascent chain is first encountered by the chaperone trigger factor (TF), which forms an open cradle underneath the ribosomal exit tunnel. This cradle serves as a passive router that channels the nascent chains to the first cotranslational event, the proteolysis event performed by the N-terminal methionine excision machinery. Although fascinating, this model clearly raises more questions than it answers. Does the data used to develop this model stand up to scrutiny and, if not, what are the alternative mechanisms that the data suggest?
在理解蛋白质生物合成过程中如何实现共翻译事件方面，最近取得了重大进展。具体而言，多项研究揭示了新生肽链从核糖体中出现后，蛋白质生物合成因子如何支持其动态过程，以确保加工和折叠机制。考虑到需要协调这一认识，最近提出的一种新的“协同模型”认为这两个过程在核糖体上同时起作用。在该模型中，新生肽链首先会遇到伴侣触发因子（TF），它在核糖体出口通道下方形成一个开放的摇篮结构。这个摇篮结构充当一个被动的路径引导器，将新生肽链引导至第一个共翻译事件，即由N端甲硫氨酸切除机制执行的蛋白水解事件。尽管这个模型很吸引人，但它显然引发的问题比回答的问题更多。用于建立这个模型的数据经得起推敲吗？如果经不起，数据所暗示的替代机制是什么？
