Identification of Small-Molecule Activators of the Ubiquitin Ligase E6AP/UBE3A and Angelman Syndrome-Derived E6AP/UBE3A Variants

• Published in: Cell chemical biology Vol. 27; no. 12; pp. 1510 - 1520.e6
• Main Authors: Offensperger, Fabian, Müller, Franziska, Jansen, Jasmin, Hammler, Daniel, Götz, Kathrin H., Marx, Andreas, Sirois, Carissa L., Chamberlain, Stormy J., Stengel, Florian, Scheffner, Martin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 17.12.2020
• Subjects: Angelman syndrome; cross-linking coupled to mass spectrometry; E6AP; fluorescence polarization; high-throughput screen; small-molecule activator; UBE3A; ubiquitin ligase; XL-MS; E6AP; ubiquitin ligase; high-throughput screen; Angelman syndrome; XL-MS; UBE3A; fluorescence polarization; cross-linking coupled to mass spectrometry; small-molecule activator
• ISSN: 2451-9456; 2451-9448; 2451-9456
• DOI: 10.1016/j.chembiol.2020.08.017

Genetic aberrations of the UBE3A gene encoding the E3 ubiquitin ligase E6AP underlie the development of Angelman syndrome (AS). Approximately 10% of AS individuals harbor UBE3A genes with point mutations, frequently resulting in the expression of full-length E6AP variants with defective E3 activity. Since E6AP exists in two states, an inactive and an active one, we hypothesized that distinct small molecules can stabilize the active state and that such molecules may rescue the E3 activity of AS-derived E6AP variants. Therefore, we established an assay that allows identifying modulators of E6AP in a high-throughput format. We identified several compounds that not only stimulate wild-type E6AP but also rescue the E3 activity of certain E6AP variants. Moreover, by chemical cross-linking coupled to mass spectrometry we provide evidence that the compounds stabilize an active conformation of E6AP. Thus, these compounds represent potential lead structures for the design of drugs for AS treatment. [Display omitted] •A fluorescence polarization-based assay to monitor E3 ligase activity was developed•Small molecules that activate E6AP/UBE3A were identified in a high-throughput screen•The compounds rescue catalytically impaired Angelman syndrome-derived E6AP variants•The compounds induce conformational rearrangements of E6AP as revealed by XL-MS Genetic aberrations of the UBE3A gene encoding the E3 ubiquitin ligase E6AP underlie the development of Angelman syndrome (AS). Here, several compounds are identified that rescue the E3 activity of certain AS-derived E6AP variants. These compounds represent potential lead structures for the design of drugs for AS treatment.