Chemical Biology Studies of Ubiquitin Transfer with Synthetic Proteins

2018 Fiscal Year Annual Research Report

• Project/Area Number: 17H01211
• Research Institution: Nagoya University
• Principal Investigator: Bode Jeffrey 名古屋大学, トランスフォーマティブ生命分子研究所, 客員教授 (90727900)
• Co-Investigator(Kenkyū-buntansha): 望田 啓子 (桑田啓子) 名古屋大学, トランスフォーマティブ生命分子研究所, 特任助教 (70624352)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: タンパク質化学 / ケミカルバイオロジー / 有機合成化学 / ユビキチン / プロテオーム解析

Outline of Annual Research Achievements

In this year, we have completed the chemical synthesis of UbcH5A, which is one of the key ubiquitin E2 conjugating enzymes. With our completed synthesis of Ubc9, the SUMO conjugating enzyme, we established that we can covalently trap known E3 ligases and form the semi-synthetic E2-SUMO covalent complex by synthetically converting the S-atom of a catalytic Cys residue to a primary amine. Using these new probes, we have begun to apply them for the identification of unknown ubiquitin E3 ligases. At the same time, we have initiated the synthesis of other E2 conjugating enzymes bearing the key mutations and photo-crosslinking residues.

Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

Our synthesis and validation of Ubc9 is complete and we will focus on using these probes for the trapping of E3 ligases, particularly those involved in the degradation of proteins that modulate the circadian rhythm. The basis synthesis of UbcH5A and preliminary biochemical validation is complete, and we will transfer this technology to co-workers who can develop this into new probes for interrogating ubiquitination.

Strategy for Future Research Activity

We have recently initiating the synthesis of a new E2 conjugating enzyme, UbcH8, which is known to mediate the transfer of ISG15, a relatively new type of ubiquitin-like modifier protein. By applying the methods and technologies developed for Ubc9, we will pursue synthetic protein probes that can identify the relatively unknown E3 ligases responsible for the conjugation of ISG15. In collaboration with Dr. Hirota and Dr. Kuwata at ITbM, we will apply our exiting probes (Ubc9, UbcH5A) for the identification of E3 ligases in different organisms, including both plant and animal cell lines. As both the Ubl modifier proteins and their conjugating enzymes are highly conserved across species, we believe the probes we have already developed (based on human sequences) will be useful for studying other organism. We expect the patterns of the the E3 ligases to be quite different.