Crystal structure of the Ube2K/E2-25K and K48-linked di-ubiquitin complex provides structural insight into the mechanism of K48-specific ubiquitin chain synthesis.
Ubiquitin-conjugating enzymes (E2) form thioester bonds with ubiquitin (Ub), which are subsequently transferred to target proteins for cellular progress. Ube2K/E2-25K (a class II E2 enzyme) contains a C-terminal ubiquitin-associated (UBA) domain that has been suggested to control ubiquitin recognition, dimerization, or poly-ubiquitin chain formation ...
Ubiquitin-conjugating enzymes (E2) form thioester bonds with ubiquitin (Ub), which are subsequently transferred to target proteins for cellular progress. Ube2K/E2-25K (a class II E2 enzyme) contains a C-terminal ubiquitin-associated (UBA) domain that has been suggested to control ubiquitin recognition, dimerization, or poly-ubiquitin chain formation. Ube2K is a special E2 because it synthesizes K48-linked poly-ubiquitin chains without E3 ubiquitin ligase. We found that a novel interaction between the acceptor di-Ub (Ub 2 ) and the auxiliary Ube2K promotes the discharging reaction and production of tri-Ub (Ub 3 ), probably by guiding and positioning the K48 (in the distal Ub) of the acceptor Ub 2 in the active site. We also determined the crystal structure of Ube2K-Ub 2 at 2.47 Å resolution. Based on our structural and biochemical data, we proposed a structural model of Ub 3 synthesis by Ube2K without E3.
Organizational Affiliation:
School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea; Steitz Center for Structural Biology, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea; Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea. Electronic address: eom@gist.ac.kr.
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