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Biochemistry. 2008 Nov 4;47(44):11446-56. doi: 10.1021/bi801115g. Epub 2008 Oct 9.

The BARD1 C-terminal domain structure and interactions with polyadenylation factor CstF-50.

Author information

  • 1Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.

Erratum in

  • Biochemistry. 2009 May 12;48(18):4008. Nazeer, I [added]; Kleiman, F E [added].

Abstract

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 one 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.

PMID:
18842000
PMCID:
PMC2654182
DOI:
10.1021/bi801115g
[PubMed - indexed for MEDLINE]
Free PMC Article
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