NMR Structural Investigations of BRCA1
EMSL Project ID
2320
Abstract
This project is aimed at gaining structural insights into the biological function and dysfunction of the breast cancer susceptibility protein known as BRCA1. Though the biological role of BRCA1 is not yet clearly understood, accumulating evidence implicates the involvement of BRCA1 in the cellular response to DNA damage in addition to other postulated functions in homologous recombination and transcriptional regulation. A full understanding of the cellular role of BRCA1 requires a detailed understanding of both the function and the structure of the protein and its interacting partners. BRCA1 is a large and complicated protein which is undoubtedly comprised of a multiplicity of functional domains. We are focusing initially on the N-terminal region of BRCA1, which contains a conserved pattern of cysteine and histidine residues found in the RING-finger family of proteins. The RING-finger is a Zn+2-binding motif found in a wide variety of proteins that are diverse both in function and origin. We have found that the RING-finger motif in BRCA1 is part of a larger N-terminal structural domain.1 This region is the site of numerous mutations found in families genetically predisposed to breast and ovarian cancer. Encompassing only 110 residues, this remarkable domain of BRCA1 has been found to interact with a number of different unrelated protein partners including; 1) the N-terminal RING domain of BARD1, a nuclear protein found to colocalize with BRCA1 in vivo, and 2) the C-terminal region of BAP1, a putative ubiquitin hydrolase. Of particular interest is the recent demonstration that the BRCA1 RING domain exhibits ubiquitin ligase activity. Ubiquitination is a multi-step process generally requiring a ubiquitin-activating enzyme (E1), a ubiquitin-transferase enzyme (E2), and a ubiquitin ligase (E3). Protein ubiquitination provides a powerful mechanism controlling pathways that include cell-cycle progression and transcriptional regulation. As components of E3-ligases, RING domains are thought to contribute to the specificity of ubiquitin conjugation reactions. Recently, the N-terminal RING region of BRCA1 has been shown to have E3 activity in the presence of the E2 ubiquitin transferase UbcH5. This activity increases dramatically when BRCA1 is complexed with the N-terminal RING domain of BARD1. Structural characterization of the interaction of BRCA1 with its various protein partners promises to yield significant insight regarding the function of the BRCA1 RING domain and further our understanding of the deleterious structural and functional consequences of known cancer pre-disposing mutations. B: Experimental Progress
Project Details
Project type
Capability Research
Start Date
2001-10-01
End Date
2002-08-30
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Brzovic PS, JR Keeffe, H Nishikawa, K Miyamoto, D Fox, M Fukuda, T Ohta, and RE Klevit. 2003. "Binding and Recognition in the Assembly of an Active BRCA1/BARD1 Ubiquitin-Ligase Complex ." Proceedings of the National Academy of Sciences of the United States of America 100(10):5646-5651.