Monomer/Oligomer Quasi-Racemic Protein Crystallography

• DOI: 10.1021/jacs.6b09545
• Publication Date: 2016-10-21T19:38:07Z
• Authors: Shuai Gao; Man Pan; Yong Zheng; Yichao Huang; Qingyun Zheng; Demeng Sun; Lining Lu; Xiaodan Tan; Xianglong Tan; Huan Lan; Jiaxing Wang; Tian Wang; Jiawei Wang; Lei Liu
• Keywords: Models, Molecular; Ubiquitin; Stereoisomerism; Amino Acid Sequence; Protein Multimerization; Crystallography, X-Ray; Protein Structure, Quaternary; 01 natural sciences; 0104 chemical sciences

Racemic or quasi-racemic crystallography recently emerges as a useful technology for solution of the crystal structures of biomacromolecules. It remains unclear to what extent the biomacromolecules of opposite handedness can differ from each other in racemic or quasi-racemic crystallography. Here we report a finding that monomeric d-ubiquitin (Ub) has propensity to cocrystallize with different dimers, trimers, and even a tetramer of l-Ub. In these cocrystals the unconnected monomeric d-Ubs can self-assemble to form pseudomirror images of different oligomers of l-Ub. This monomer/oligomer cocrystallization phenomenon expands the concept of racemic crystallography. Using the monomer/oligomer cocrystallization technology we obtained, for the first time the X-ray structures of linear M1-linked tri- and tetra-Ubs and a K11/K63-branched tri-Ub.