8k8t
Structure of CUL3-RBX1-KLHL22 complex
Structural highlights
DiseaseCUL3_HUMAN Pseudohypoaldosteronism type 2E. Defects in CUL3 are the cause of Pseudohypoaldosteronism type 2E (PHA2E) [MIM:614496. An autosomal dominant disorder characterized by severe hypertension, hyperkalemia, hyperchloremia, hyperchloremic metabolic acidosis, and correction of physiologic abnormalities by thiazide diuretics.[1] FunctionCUL3_HUMAN Core component of multiple cullin-RING-based BCR (BTB-CUL3-RBX1) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1 (By similarity). The functional specificity of the BCR complex depends on the BTB domain-containing protein as the susbstrate recognition component. BCR(SPOP) is involved in ubiquitination of BMI1/PCGF4, H2AFY and DAXX, and probably GLI2 or GLI3. BCR(KLHL9-KLHL13) controls the dynamic behavior of AURKB on mitotic chromosomes and thereby coordinates faithful mitotic progression and completion of cytokinesis. BCR(KLHL12) is involved in ER-Golgi transport by regulating the size of COPII coats, thereby playing a key role in collagen export, which is required for embryonic stem (ES) cells division: BCR(KLHL12) acts by mediating monoubiquitination of SEC31 (SEC31A or SEC31B). BCR(KLHL3) acts as a regulator of ion transport in the distal nephron; possibly by mediating ubiquitination of SLC12A3/NCC. Involved in ubiquitination of cyclin E and of cyclin D1 (in vitro) thus involved in regulation of G1/S transition.[2] [3] [4] [5] [6] [7] Publication Abstract from PubMedThe CUL3-RING E3 ubiquitin ligases (CRL3s) play an essential role in response to extracellular nutrition and stress stimuli. The ubiquitin ligase function of CRL3s is activated through dimerization. However, how and why such a dimeric assembly is required for its ligase activity remains elusive. Here, we report the cryo-EM structure of the dimeric CRL3(KLHL22) complex and reveal a conserved N-terminal motif in CUL3 that contributes to the dimerization assembly and the E3 ligase activity of CRL3(KLHL22). We show that deletion of the CUL3 N-terminal motif impairs dimeric assembly and the E3 ligase activity of both CRL3(KLHL22) and several other CRL3s. In addition, we found that the dynamics of dimeric assembly of CRL3(KLHL22) generates a variable ubiquitination zone, potentially facilitating substrate recognition and ubiquitination. These findings demonstrate that a CUL3 N-terminal motif participates in the assembly process and provide insights into the assembly and activation of CRL3s. A conserved N-terminal motif of CUL3 contributes to assembly and E3 ligase activity of CRL3(KLHL22).,Wang W, Liang L, Dai Z, Zuo P, Yu S, Lu Y, Ding D, Chen H, Shan H, Jin Y, Mao Y, Yin Y Nat Commun. 2024 May 6;15(1):3789. doi: 10.1038/s41467-024-48045-2. PMID:38710693[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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