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oai:drum.lib.umd.edu:1903/187822017-06-13T10:34:29Zcom_1903_11812com_1903_12com_1903_2col_1903_2752col_1903_3

Fushman, David Sundar, Adithya Digital Repository at the University of Maryland University of Maryland (College Park, Md.) Biochemistry 2016-09-08T05:42:22Z 2016-09-08T05:42:22Z 2016 https://doi.org/10.13016/M2XN6V http://hdl.handle.net/1903/18782 K48-linked di-ubiquitin exists in a dynamic equilibrium between open and closed states. The structure of K48-Ub2 in the closed conformation features a hydrophobic interface formed between the two Ub domains. The same hydrophobic residues at the interface are involved in binding to ubiquitin-associated (UBA) domains. Cyclization of K48-Ub2 should limit the range of conformations available for such interactions. Interestingly, cyclic K48-linked Ub2 (cycUb2) has been found in vivo and can be isolated in vitro to study its structure and dynamics. In this study, a crystal structure of cycUb2 was obtained, and the dynamics of cycUb2 were characterized by solution NMR. The crystal structure of cycUb2, which is in agreement with solution NMR data, is closed with the hydrophobic patches of each Ub domain buried at the interface. Despite its structural constraints, cycUb2 was still able to interact with UBA domains, albeit with lower affinity. en STRUCTURAL AND FUNCTIONAL STUDIES OF CYCLIC K48-LINKED DIUBIQUITIN Thesis Biochemistry cyclic K48-linked di-ubiquitin dynamics protein NMR structure ubiquitin open.access