Structural mechanisms of multimeric BTB E3 ligases and interactors

Thesis

In recent years, E3 ligases and ubiquitination biology have garnered increased attention due to their critical role in emerging field targeted protein degradation field (TPD). However, many E3 ligases associate with multiple interactors and are often implicated in several diverse cellular processes. The ability to utilise these E3 ligases relies on complete characterisation of their structural mechanisms and interactor partners.

This thesis presents investigations into three distinct multimeric cullin-RING ligases. KCTD9 is a unique member of an unusual set of E3 ligases that typically assemble into higher-order assemblies. Newly generated structural data has provided insights into its function, while affinity mass spectrometry has identified a shortlist of potential interactors that may elucidate KCTD9’s role in natural killer cell development.

Dimeric KLHL12 is a rare example of an E3 ligase that can engage multiple types of interactors through a shared recognition motif. Structural data confirm, that despite some variation in protein sequence among interactors, they adopt a common binding mode.

Finally, attempts were made to setup a reproducible crystal system and establish biophysical assays for the E3 ligase FBXO31, in order to screen compounds selected by virtual ligand screening. However, these experiments were waylaid by previous studies of FBXO31, in which its interactions with Cyclin D1 were poorly characterised.

Overall, these findings contribute to the growing understanding of E3 ligases, and this will aid in TPD developments.

Authors: Ramdass, AE

• DOI: 10.5287/ora-r5oqq688m
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: KCTD9; KLHL12; E3 ligase; FBXO31