Quasi-Racemic X-ray Structures of K27-Linked Ubiquitin Chains Prepared by Total Chemical Synthesis

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• 作者：Man Pan ; Shuai Gao ; Yong Zheng ; Xiaodan Tan ; Huan Lan ; Xianglong Tan ; Demeng Sun ; Lining Lu ; Tian Wang ; Qingyun Zheng ; Yichao Huang ; Jiawei Wang ; Lei Liu
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：138
• 期：23
• 页码：7429-7435
• 全文大小：551K
• 年卷期：0
• ISSN：1520-5126

文摘

Quasi-racemic crystallography has been used to determine the X-ray structures of K27-linked ubiquitin (Ub) chains prepared through total chemical synthesis. Crystal structures of K27-linked di- and tri-ubiquitins reveal that the isopeptide linkages are confined in a unique buried conformation, which provides the molecular basis for the distinctive function of K27 linkage compared to the other seven Ub chains. K27-linked di- and triUb were found to adopt different structural conformations in the crystals, one being symmetric whereas the other triangular. Furthermore, bioactivity experiments showed that the ovarian tumor family de-ubiquitinase 2 significantly favors K27-linked triUb than K27-linked diUb. K27-linked triUb represents the so-far largest chemically synthesized protein (228 amino acids) that has been crystallized to afford a high-resolution X-ray structure.