Solution Structure, Backbone Dynamics, and Association Behavior of the C-Terminal BRCT Domain from the Breast Cancer-Associated Protein BRCA1

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• 作者：Olaf J. Gaiser ; Linda J. Ball ; Peter Schmieder ; Dietmar Leitner ; Holger Strauss ; Martin Wahl ; Ronald K&uuml ; hne ; Hartmut Oschkinat ; and Udo Heinemann
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：December 28, 2004
• 年：2004
• 卷：43
• 期：51
• 页码：15983 - 15995
• 全文大小：1098K
• 年卷期：v.43,no.51(December 28, 2004)
• ISSN：1520-4995

文摘

BRCA1 is a tumor suppressor protein associated with breast and ovarian cancer. The C-terminalregion of BRCA1 consists of two closely spaced BRCT domains which mediate essential biologicalfunctions, including regulation of transcription and control of cell-cycle progression by their interactionwith phosphorylated effector proteins. Here we report the NMR structure of the isolated C-terminal BRCTdomain (BRCT-c) from human BRCA1. BRCT-c is well-structured in solution, folding independently inthe absence of its BRCT-n counterpart. Ultracentrifugation experiments and size exclusion chromatographyreveal that BRCT-c exists as a monomer under near-physiological conditions. Dynamics measurementsfrom NMR data show three loops which coincide with the most variable sequence regions in BRCTdomains, to be genuinely flexible in solution. The solution structure of BRCT-c shows subtle conformationalchanges when compared to the crystal structure of BRCT-c in the tandem repeat of BRCA1. These affectsites involved in formation of the BRCT-n-BRCT-c interface and the binding to phosphoserine-containingpeptides. The results suggest that the presence of native BRCT-n and a properly aligned BRCT-n-BRCT-cinterface are essential if BRCT-c is to adopt a biologically active conformation. Structural consequencesof cancer-associated mutations and biological implications of the dynamic behavior are discussed.