skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Crystal Structure of the BARD1 BRCT Domains

Abstract

The interaction of the breast tumor suppressor BRCA1 with the protein BARD1 results in the formation of a heterodimeric complex that has ubiquitin ligase activity and plays central roles in cell cycle checkpoint control and DNA repair. Both BRCA1 and BARD1 possess a pair of tandem BRCT domains that interact in a phosphorylation-dependent manner with target proteins. We determined the crystal structure of the human BARD1 BRCT repeats (residues 568-777) at 1.9 {angstrom} resolution. The composition and structure of the BARD1 phosphoserine-binding pocket P{sub 1} are strikingly similar to those of the BRCA1 and MDC1 BRCT domains, suggesting a similar mode of interaction with the phosphate group of the ligand. By contrast, the BARD1 BRCT selectivity pocket P{sub 2} exhibits distinct structural features, including two prominent histidine residues, His685 and His686, which may be important for ligand binding. The protonation state of these histidines has a marked effect on the calculated electrostatic potential in the vicinity of P{sub 2}, raising the possibility that ligand recognition may be regulated by changes in pH. Importantly, the BARD1 BRCT structure provides insights into the mechanisms by which the cancer-associated missense mutations C645R, V695L, and S761N may adversely affect the structure and function ofmore » BARD1.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929941
Report Number(s):
BNL-80536-2008-JA
Journal ID: ISSN 0006-2960; TRN: US200822%%1110
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry; Journal Volume: 46
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CELL CYCLE; CONTROL; CRYSTAL STRUCTURE; DNA REPAIR; ELECTROSTATICS; ELECTRIC POTENTIAL; FUNCTIONS; HISTIDINE; HUMAN POPULATIONS; INTERACTIONS; LIGANDS; LIGASES; MAMMARY GLANDS; MUTATIONS; NEOPLASMS; PHOSPHATES; PROTEINS; RESIDUES; national synchrotron light source

Citation Formats

Birrane,G., Varma, A., Soni, A., and Ladias, J.. Crystal Structure of the BARD1 BRCT Domains. United States: N. p., 2007. Web. doi:10.1021/bi700323t.
Birrane,G., Varma, A., Soni, A., & Ladias, J.. Crystal Structure of the BARD1 BRCT Domains. United States. doi:10.1021/bi700323t.
Birrane,G., Varma, A., Soni, A., and Ladias, J.. Mon . "Crystal Structure of the BARD1 BRCT Domains". United States. doi:10.1021/bi700323t.
@article{osti_929941,
title = {Crystal Structure of the BARD1 BRCT Domains},
author = {Birrane,G. and Varma, A. and Soni, A. and Ladias, J.},
abstractNote = {The interaction of the breast tumor suppressor BRCA1 with the protein BARD1 results in the formation of a heterodimeric complex that has ubiquitin ligase activity and plays central roles in cell cycle checkpoint control and DNA repair. Both BRCA1 and BARD1 possess a pair of tandem BRCT domains that interact in a phosphorylation-dependent manner with target proteins. We determined the crystal structure of the human BARD1 BRCT repeats (residues 568-777) at 1.9 {angstrom} resolution. The composition and structure of the BARD1 phosphoserine-binding pocket P{sub 1} are strikingly similar to those of the BRCA1 and MDC1 BRCT domains, suggesting a similar mode of interaction with the phosphate group of the ligand. By contrast, the BARD1 BRCT selectivity pocket P{sub 2} exhibits distinct structural features, including two prominent histidine residues, His685 and His686, which may be important for ligand binding. The protonation state of these histidines has a marked effect on the calculated electrostatic potential in the vicinity of P{sub 2}, raising the possibility that ligand recognition may be regulated by changes in pH. Importantly, the BARD1 BRCT structure provides insights into the mechanisms by which the cancer-associated missense mutations C645R, V695L, and S761N may adversely affect the structure and function of BARD1.},
doi = {10.1021/bi700323t},
journal = {Biochemistry},
number = ,
volume = 46,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • BARD1 is the constitutive nuclear partner to the breast and ovarian cancer specific tumor suppressor BRCA1. Together, they form a heterodimeric complex responsible for maintaining genomic stability through nuclear functions involving DNA damage signaling and repair, transcriptional regulation, and cell cycle control.
  • No abstract prepared.
  • The tandem BRCA1 C-terminal (BRCT) domains are phospho-serine/threonine recognition modules essential for the function of BRCA1. Recent studies suggest that acetyl-CoA carboxylase 1 (ACC1), an enzyme with crucial roles in de novo fatty acid biosynthesis and lipogenesis and essential for cancer cell survival, may be a novel binding partner for BRCA1, through interactions with its BRCT domains. We report here the crystal structure at 3.2 Angstroms resolution of human BRCA1 BRCT domains in complex with a phospho-peptide from human ACC1 (p-ACC1 peptide, with the sequence 1258-DSPPQ-pS-PTFPEAGH-1271), which provides molecular evidence for direct interactions between BRCA1 and ACC1. The p-ACC1 peptidemore » is bound in an extended conformation, located in a groove between the tandem BRCT domains. There are recognizable and significant structural differences to the binding modes of two other phospho-peptides to these domains, from BACH1 and CtIP, even though they share a conserved pSer-Pro-(Thr/Val)-Phe motif. Our studies establish a framework for understanding the regulation of lipid biosynthesis by BRCA1 through its inhibition of ACC1 activity, which could be a novel tumor suppressor function of BRCA1.« less
  • The BARD1 N-terminal RING domain binds BRCA1 while the BARD1 C-terminal ankyrin and tandem BRCT repeat domains bind CstF-50 to modulate mRNA processing and RNAP II stability in response to DNA damage. Here we characterize the BARD1 structural biochemistry responsible for CstF- 50 binding. The crystal structure of the BARD1 BRCT domain uncovers a degenerate phosphopeptide binding pocket lacking the key arginine required for phosphopeptide interactions in other BRCT proteins.Small angle X-ray scattering together with limited proteolysis results indicates that ankyrin and BRCT domains are linked by a flexible tether and do not adopt a fixed orientation relative to onemore » another. Protein pull-down experiments utilizing a series of purified BARD1 deletion mutants indicate that interactions between the CstF-50 WD-40 domain and BARD1 involve the ankyrin-BRCT linker but do not require ankyrin or BRCT domains. The structural plasticity imparted by the ANK-BRCT linker helps to explain the regulated assembly of different protein BARD1 complexes with distinct functions in DNA damage signaling including BARD1-dependent induction of apoptosis plus p53 stabilization and interactions. BARD1 architecture and plasticity imparted by the ANK-BRCT linker are suitable to allow the BARD1 C-terminus to act as a hub with multiple binding sites to integrate diverse DNA damage signals directly to RNA polymerase.« less
  • The N-terminal RING domain of the breast and ovarian cancer tumor suppressor BRCA1 interacts with multiple cognate proteins, including the RING protein, BARD1. Proper function of the BRCA1 RING domain is critical, as evidenced by the many cancer-predisposing mutations found within this domain. We present the solution structure of the N-terminal RING domain heterodimer of BRCA1 and BARD1. Comparison with the RAG1 RING homodimer reveals the structural diversity of complexes formed by interactions between different RING domains. The BRCA1/BARD1 structure provides a model for its ubiquitin ligase activity, illustrates how the BRCA1 RING domain can be involved in associations withmore » multiple protein partners, and provdes a framework for understanding cancer-causing mutations at the molecular level.« less