The BARD1 C-Terminal Domain Structure and Interactions with Polyadenylation Factor CstF-50
- Resource Type
- Journal Article
- Authors
- Source
- Biochemistry
- Subject
- 59 APOPTOSIS
ARCHITECTURE
ARGININE
BIOCHEMISTRY
CRYSTAL STRUCTURE
DNA DAMAGES
DOMAIN STRUCTURE
INDUCTION
MUTANTS
ORIENTATION
PLASTICITY
PROCESSING
PROTEINS
PROTEOLYSIS
RNA POLYMERASES
SCATTERING
STABILITY
STABILIZATION BARD1 CstF-50 Polyadenylation SAXS
BARD1 CstF-50 Polyadenylation SAXS
- Language
- English
- ISSN
- 0006-2960
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.