Abstract
SummaryBTB-Kelch proteins form the largest subfamily of Cullin-RING E3 ligases, yet their substrate complexes are mapped and structurally characterized only for KEAP1 and KLHL3. KLHL20 is a related CUL3-dependent ubiquitin ligase linked to autophagy, cancer, and Alzheimer's disease that promotes the ubiquitination and degradation of substrates including DAPK1, PML, and ULK1. We identified an “LPDLV”-containing motif in the DAPK1 death domain that determines its recruitment and degradation by KLHL20. A 1.1-Å crystal structure of a KLHL20 Kelch domain-DAPK1 peptide complex reveals DAPK1 binding as a loose helical turn that inserts deeply into the central pocket of the Kelch domain to contact all six blades of the β propeller. Here, KLHL20 forms salt-bridge and hydrophobic interactions including tryptophan and cysteine residues ideally positioned for covalent inhibitor development. The structure highlights the diverse binding modes of β-propeller domains versus linear grooves and suggests a new target for structure-based drug design.
Highlights
Ubiquitination by E1-E2-E3 enzyme cascades is the major mechanism by which cells mark proteins for degradation, but can facilitate protein trafficking, transcriptional control, and cell signaling (Hershko and Ciechanover, 1998; Rape, 2018)
Kelch-like protein 20 (KLHL20, known as KLEIP) is a member of the BTB-Kelch family that assembles with CUL3 and RBX1 to form a multi-subunit Cullin-RING E3 ligase (Geyer et al, 2003; Hara et al, 2004; Pintard et al, 2004)
Catalysis is enhanced by CUL3 neddylation, which stabilizes the correct geometry of the complex for ubiquitin transfer (Duda et al, 2008)
Summary
Ubiquitination by E1-E2-E3 enzyme cascades is the major mechanism by which cells mark proteins for degradation, but can facilitate protein trafficking, transcriptional control, and cell signaling (Hershko and Ciechanover, 1998; Rape, 2018). Kelch-like protein 20 (KLHL20, known as KLEIP) is a member of the BTB-Kelch family that assembles with CUL3 and RBX1 to form a multi-subunit Cullin-RING E3 ligase (Geyer et al, 2003; Hara et al, 2004; Pintard et al, 2004) These complex E3 ligases use the RBX1 subunit to engage a charged E2-ubiquitin pair before transferring the ubiquitin to substrates captured by the BTB-Kelch protein (Genschik et al, 2013; Petroski and Deshaies, 2005). The majority of substrates identified for KLHL20 have been targeted for proteasomal degradation, suggesting their modification by Lys48-linked polyubiquitin chains (Chen et al, 2016) These include the substrates DAPK1 (Lee et al, 2010), PML (Yuan et al, 2011), PDZ-RhoGEF (Lin et al, 2011), and ULK1 (Liu et al, 2016). KLHL20 plays an important role in protein trafficking by targeting coronin 7 to the trans-Golgi network through atypical K33-linked polyubiquitination (Yuan et al, 2014)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
