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Structure and dynamics of a pentameric KCTD5/CUL3/Gβγ E3 ubiquitin ligase complex.

Duc Minh NguyenDeanna H RathDominic DevostDarlaine PétrinRobert RizkAlan X JiNaveen NarayananDarren YongAndrew ZhaiDouglas A KuntzMaha U Q MianNeil C PomroyAlexander F A KeszeiSamir BenlekbirMohammad T Mazhab-JafariJohn L RubinsteinTerence E HébertGilbert G Privé
Published in: Proceedings of the National Academy of Sciences of the United States of America (2024)
Heterotrimeric G proteins can be regulated by posttranslational modifications, including ubiquitylation. KCTD5, a pentameric substrate receptor protein consisting of an N-terminal BTB domain and a C-terminal domain, engages CUL3 to form the central scaffold of a cullin-RING E3 ligase complex (CRL3 KCTD5 ) that ubiquitylates Gβγ and reduces Gβγ protein levels in cells. The cryo-EM structure of a 5:5:5 KCTD5/CUL3 NTD /Gβ 1 γ 2 assembly reveals a highly dynamic complex with rotations of over 60° between the KCTD5 BTB /CUL3 NTD and KCTD5 CTD /Gβγ moieties of the structure. CRL3 KCTD5 engages the E3 ligase ARIH1 to ubiquitylate Gβγ in an E3-E3 superassembly, and extension of the structure to include full-length CUL3 with RBX1 and an ARIH1~ubiquitin conjugate reveals that some conformational states position the ARIH1~ubiquitin thioester bond to within 10 Å of lysine-23 of Gβ and likely represent priming complexes. Most previously described CRL/substrate structures have consisted of monovalent complexes and have involved flexible peptide substrates. The structure of the KCTD5/CUL3 NTD /Gβγ complex shows that the oligomerization of a substrate receptor can generate a polyvalent E3 ligase complex and that the internal dynamics of the substrate receptor can position a structured target for ubiquitylation in a CRL3 complex.
Keyphrases
  • amino acid
  • induced apoptosis
  • oxidative stress
  • signaling pathway
  • mass spectrometry
  • protein protein