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The BARD1 C-Terminal Domain Structure and Interactions with Polyadenylation Factor CstF-50

[Image: see text] 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 bi...

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Detalles Bibliográficos
Autores principales: Edwards, Ross A., Lee, Megan S., Tsutakawa, Susan E., Williams, R. Scott, Tainer, John A., Glover, J. N. Mark
Formato: Texto
Lenguaje:English
Publicado: American Chemical Society 2008
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2654182/
https://www.ncbi.nlm.nih.gov/pubmed/18842000
http://dx.doi.org/10.1021/bi801115g
Descripción
Sumario:[Image: see text] 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.