来自加州理工学院的研究人员近期接连破解了一蛋白机制之谜，发现了泛素如何添加到控制细胞周期的特异性蛋白上的机制，该项成果发表在近期Science权威刊物上。
研究人员分析了大肠杆菌中的信号识别颗粒（signal recognition particle,SRP）途径，发现机体能通过一系列的检测点排除错误，从而确保蛋白靶向的精确性。
正确的蛋白定位对于所有的细胞来说都是至关重要的，但是科学家们对于蛋白靶向途径中如何保存高度的忠实性的机制了解并不多。为了解开这一迷题，在这篇文章中，研究人员针对SRP途径展开了研究，SRP途径是一个高度保守的蛋白靶向途径，先后在真核生物、原核生物和古细菌中被发现，在原核生物中SRP途径主要由Ffh、FtsY和scRNA组成。
研究人员通过生物物理分析方法，发现机体能通过一系列的检测点排除错误，从而确保蛋白靶向的精确性。这种机制也许能应用到其它选择性的信号识别途径中。(生物谷Bioon.com)
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Science DOI: 10.1126/science.1186743
Sequential Checkpoints Govern Substrate Selection During Cotranslational Protein Targeting
Xin Zhang, Rumana Rashid,* Kai Wang, Shu-ou Shan
Proper protein localization is essential for all cells. However, the precise mechanism by which high fidelity is achieved is not well understood for any protein-targeting pathway. To address this fundamental question, we investigated the signal recognition particle (SRP) pathway in Escherichia coli, which delivers proteins to the bacterial inner membrane through recognition of signal sequences on cargo proteins. Fidelity was thought to arise from the inability of SRP to bind strongly to incorrect cargos. Using biophysical assays, we found that incorrect cargos were also rejected through a series of checkpoints during subsequent steps of targeting. Thus, high fidelity of substrate selection is achieved through the cumulative effect of multiple checkpoints; this principle may be generally applicable to other pathways involving selective signal recognition.
Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
* Present address: Department of Molecular Medicine, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.
