Enhancement of BRCA1 E3 ubiquitin ligase activity through direct interaction with the BARD1 protein

Yan Xia, Gerald M. Pao, Hongwu Chen, Inder M. Verma, Tony Hunter

Research output: Contribution to journalArticle

153 Citations (Scopus)

Abstract

The breast and ovarian cancer-specific tumor suppressor RING finger protein BRCA1 has been identified as an E3 ubiquitin (Ub) ligase through in vitro studies, which demonstrated that its RING finger domain can autoubiquitylate and monoubiquitylate histone H2A when supplied with Ub, E1, and UBC4 (E2). Here we report that the E3 ligase activity of the N-terminal 110 amino acid residues of BRCA1, which encodes a stable domain containing the RING finger, as well as that of the full-length BRCA1, was significantly enhanced by the BARD1 protein (residues 8-142), whose RING finger domain itself lacked Ub ligase activity in vitro. The results of mutagenesis studies indicate that the enhancement of BRCA1 E3 ligase activity by BARD1 depends on direct interaction between the two proteins. Using K48A and K63A Ub mutants, we found that BARD1 stimulated the formation of both Lys48- and Lys63-linked poly-Ub chains. However, the enhancement of BRCA1 autoubiquitylation by BARD1 mostly resulted in poly-Ub chains linked through Lys63, which could potentially activate biological pathways other than BRCA1 degradation. We also found that co-expression of BRCA1 and BARD1 in living cells increased the abundance and stability of both proteins and that this depended on their ability to heterodimerize.

Original languageEnglish (US)
Pages (from-to)5255-5263
Number of pages9
JournalJournal of Biological Chemistry
Volume278
Issue number7
DOIs
StatePublished - Feb 14 2003

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RING Finger Domains
Ubiquitin-Protein Ligases
Ubiquitin
Polyubiquitin
BRCA1 Protein
Mutagenesis
Proteins
Protein Stability
Ligases
Ovarian Neoplasms
Histones
Tumors
Cells
Breast Neoplasms
Amino Acids
Degradation
Neoplasms
In Vitro Techniques

ASJC Scopus subject areas

  • Biochemistry

Cite this

Enhancement of BRCA1 E3 ubiquitin ligase activity through direct interaction with the BARD1 protein. / Xia, Yan; Pao, Gerald M.; Chen, Hongwu; Verma, Inder M.; Hunter, Tony.

In: Journal of Biological Chemistry, Vol. 278, No. 7, 14.02.2003, p. 5255-5263.

Research output: Contribution to journalArticle

Xia, Yan ; Pao, Gerald M. ; Chen, Hongwu ; Verma, Inder M. ; Hunter, Tony. / Enhancement of BRCA1 E3 ubiquitin ligase activity through direct interaction with the BARD1 protein. In: Journal of Biological Chemistry. 2003 ; Vol. 278, No. 7. pp. 5255-5263.
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