Mammalian DET1 regulates Cul4A activity and forms stable complexes with E2 ubiquitin-conjugating enzymes

Elah Pick, On Sun Lau, Tomohiko Tsuge, Suchithra Menon, Yingchun Tong, Naoshi Dohmae, Scott M. Plafker, Wang Deng Xing, Ning Wei

Research output: Contribution to journalArticlepeer-review

Abstract

DET1 (de-etiolated 1) is an essential negative regulator of plant light responses, and it is a component of the Arabidopsis thaliana CDD complex containing DDB1 and COP10 ubiquitin E2 variant. Human DET1 has recently been isolated as one of the DDB1- and Cul4A-associated factors, along with an array of WD40-containing substrate receptors of the Cul4A-DDB1 ubiquitin ligase. However, DET1 differs from conventional substrate receptors of cullin E3 ligases in both biochemical behavior and activity. Here we report that mammalian DET1 forms stable DDD-E2 complexes, consisting of DDB1, DDA1 (DET1, DDB1 associated 1), and a member of the UBE2E group of canonical ubiquitin-conjugating enzymes. DDD-E2 complexes interact with multiple ubiquitin E3 ligases. We show that the E2 component cannot maintain the ubiquitin thioester linkage once bound to the DDD core, rendering mammalian DDD-E2 equivalent to the Arabidopsis CDD complex. While free UBE2E-3 is active and able to enhance UbcH5/Cul4A activity, the DDD core specifically inhibits Cul4A-dependent polyubiquitin chain assembly in vitro. Overexpression of DET1 inhibits UV-induced CDT1 degradation in cultured cells. These findings demonstrate that the conserved DET1 complex modulates Cul4A functions by a novel mechanism.

Original languageEnglish
Pages (from-to)4708-4719
Number of pages12
JournalMolecular and Cellular Biology
Volume27
Issue number13
DOIs
StatePublished - Jul 2007
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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