The Ufd1 cofactor determines the linkage specificity of polyubiquitin chain engagement by the AAA+ ATPase Cdc48.
Mol Cell
; 83(5): 759-769.e7, 2023 03 02.
Article
en En
| MEDLINE
| ID: mdl-36736315
ABSTRACT
The AAA+ ATPase Cdc48 utilizes the cofactor Ufd1/Npl4 to bind and thread polyubiquitinated substrates for their extraction from complexes or membranes and often for subsequent proteasomal degradation. Previous studies indicated that Cdc48 engages polyubiquitin chains through the Npl4-mediated unfolding of an initiator ubiquitin; yet, the underlying principles remain largely unknown. Using FRET-based assays, we revealed the mechanisms and kinetics of ubiquitin unfolding, insertion into the ATPase, and unfolding of the ubiquitin-attached substrate. We found that Cdc48 uses Ufd1's UT3 domain to bind a K48-linked ubiquitin on the initiator's proximal side of the chain, thereby directing the initiator toward rapid unfolding by Npl4 and engagement by Cdc48. Ubiquitins on the initiator's distal side increase substrate affinity and facilitate unfolding but impede substrate release from Cdc48-Ufd1/Npl4 in the absence of additional cofactors. Our findings explain how Cdc48-UN efficiently processes substrates with K48-linked chains of 4-6 ubiquitins, which represent most cellular polyubiquitinated proteins.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Saccharomyces cerevisiae
/
Poliubiquitina
Idioma:
En
Revista:
Mol Cell
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2023
Tipo del documento:
Article
País de afiliación:
Estados Unidos