4OFB

Crystal structure of human BRCA1 BRCT in complex with nonphosphopeptide inhibitor

Summary for 4OFB

• Entry DOI: 10.2210/pdb4ofb/pdb
• Descriptor: Breast cancer type 1 susceptibility protein, nonphosphopeptide inhibitor (2 entities in total)
• Functional Keywords: brct domain, dsb dna damage repair, non-phosphorylated peptide, protein binding
• Biological source: Homo sapiens (human)
• Cellular location: Nucleus . Isoform 3: Cytoplasm. Isoform 5: Cytoplasm : P38398
• Total number of polymer chains: 2
• Total formula weight: 26185.02

Authors

Sun, L.,Edwards, R.A.,Glover, J.N.M. (deposition date: 2014-01-14, release date: 2015-04-15, Last modification date: 2025-03-26)

Primary citation

White, E.R.,Sun, L.,Ma, Z.,Beckta, J.M.,Danzig, B.A.,Hacker, D.E.,Huie, M.,Williams, D.C.,Edwards, R.A.,Valerie, K.,Glover, J.N.,Hartman, M.C.
Peptide Library Approach to Uncover Phosphomimetic Inhibitors of the BRCA1 C-Terminal Domain.
Acs Chem.Biol., 10:1198-1208, 2015

PubMed Abstract: Many intracellular protein-protein interactions are mediated by the phosphorylation of serine, and phosphoserine-containing peptides can inhibit these interactions. However, hydrolysis of the phosphate by phosphatases, and the poor cell permeability associated with phosphorylated peptides has limited their utility in cellular and in vivo contexts. Compounding the problem, strategies to replace phosphoserine in peptide inhibitors with easily accessible mimetics (such as Glu or Asp) routinely fail. Here, we present an in vitro selection strategy for replacement of phosphoserine. Using mRNA display, we created a 10 trillion member structurally diverse unnatural peptide library. From this library, we found a peptide that specifically binds to the C-terminal domain (BRCT)2 of breast cancer associated protein 1 (BRCA1) with an affinity comparable to phosphorylated peptides. A crystal structure of the peptide bound reveals that the pSer-x-x-Phe motif normally found in BRCA1 (BRCT)2 binding partners is replaced by a Glu-x-x-4-fluoroPhe and that the peptide picks up additional contacts on the protein surface not observed in cognate phosphopeptide binding. Expression of the peptide in human cells led to defects in DNA repair by homologous recombination, a process BRCA1 is known to coordinate. Overall, this work validates a new in vitro selection approach for the development of inhibitors of protein-protein interactions mediated by serine phosphorylation.

PubMed: 25654734
DOI: 10.1021/cb500757u

Experimental method

X-RAY DIFFRACTION (3.05 Å)