Release of ubiquitin-charged Cdc34-S - Ub from the RING domain is essential for ubiquitination of the SCF(Cdc4)-bound substrate Sic1.

Published

Journal Article

The S. cerevisiae SCF(Cdc4) is a prototype of RING-type SCF E3s, which recruit substrates for polyubiquitination by the Cdc34 ubiquitin-conjugating enzyme. Current models propose that Cdc34 ubiquitinates the substrate while remaining bound to the RING domain. In contrast, we found that the formation of a ubiquitin thiol ester regulates the Cdc34/SCF(Cdc4) binding equilibrium by increasing the dissociation rate constant, with only a minor effect on the association rate. By using a F72VCdc34 mutant with increased affinity for the RING domain, we demonstrate that release of ubiquitin-charged Cdc34-S - Ub from the RING is essential for ubiquitination of the SCF(Cdc4)-bound substrate Sic1. Release of ubiquitin-charged E2 from E3 prior to ubiquitin transfer is a previously unrecognized step in ubiquitination, which can explain both the modification of multiple lysines on the recruited substrate and the extension of polyubiquitin chains. We discuss implications of this finding for function of other ubiquitin ligases.

Full Text

Duke Authors

Cited Authors

  • Deffenbaugh, AE; Scaglione, KM; Zhang, L; Moore, JM; Buranda, T; Sklar, LA; Skowyra, D

Published Date

  • September 2003

Published In

Volume / Issue

  • 114 / 5

Start / End Page

  • 611 - 622

PubMed ID

  • 13678584

Pubmed Central ID

  • 13678584

Electronic International Standard Serial Number (EISSN)

  • 1097-4172

International Standard Serial Number (ISSN)

  • 0092-8674

Digital Object Identifier (DOI)

  • 10.1016/s0092-8674(03)00641-x

Language

  • eng