The substrates of FAT10ylation and their proteolytic targeting (C01)

• Subject Area: Biochemistry
• Term: from 2012 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 189682160

The conjugation of proteins with the ubiquitin-like modifier FAT10 leads to their rapid degradation by the 26S proteasome. The E1 enzyme (UBA6) and an E2 enzyme (USE1) for FAT10 conjugation have been described, but E3 ligases and FAT10 deconjugating enzymes are presently unknown. We have identified two E3 ligases as substrates of FAT10ylation and shown that at least one of them has FAT10 ligase activity. We will now fully characterize these two and other candidate enzymes with respect to their FAT10ylation activity in vitro and in cells, their regulation, substrate specificity, and biological function. Since both ligases are involved in mitophagy and since proteins of depolarized mitochondria become FAT10ylated, a role of FAT10 in mitophagy regulation will be investigated. Using newly generated FAT10-based active site-directed probes, we will search for FAT10 deconjugating enzymes and a novel cytokine-induced E2 enzyme for FAT10.

• DFG Programme: Collaborative Research Centres
• Subproject of: SFB 969: Chemical and Biological Principles of Cellular Proteostasis
• Applicant Institution: Universität Konstanz
• Project Heads: Professor Dr. Marcus Groettrup (†); Professorin Dr. Erika Isono, since 6/2022