Structure of a second BRCT domain identified in the Nijmegen breakage syndrome protein Nbs1 and its function in an MDC1-dependent localization of Nbs1 to DNA damage sites

JOURNAL OF MOLECULAR BIOLOGY

卷:381

Article

Xu, Chao¹  Wu, Liming²  Cui, Gaofeng¹  Botuyan, Maria Victoria¹  Chen, Junjie²  Mer, Georges¹ 

[1] Mayo Clin, Coll Med, Dept Biochem & Mol Biol, Rochester, MN 55905 USA

[2] Yale Univ, Sch Med, Dept Therapeut Radiol, New Haven, CT 06520 USA

关键词: Nijemegen breakage syndrome;    Nbs1;    MDC1;    DNA damage response;    BRCT domain;   

DOI  :  10.1016/j.jmb.2008.05.087

来源: Elsevier

【 摘 要 】

The Nijmegen breakage syndrome protein Nbs1 is a component of the MRN (Mre11-Rad50-Nbs1) complex, central to the DNA damage response. While Nbs1 is generally believed to encompass a forkhead-associated domain linked to a breast cancer C-terminal (BRCT) domain, to date there is no experimental information on its three-dimensional structure. Through nuclear magnetic resonance (NMR) three-dimensional structure determination, we demonstrate that there is a second BRCT domain (BRCT2) in Nbs1. The domain has the characteristic BRCT topology, but with a long insertion shown to be flexible by NMR relaxation measurements. In the absence of sequence similarity to other proteins, a search for structural analogs of BRCT2 returned the second BRCT domain of the tandem BRCT repeats of cell cycle checkpoint proteins MDC1 (mediator of DNA damage checkpoint protein 1) and BRCA1 (breast cancer protein 1), suggesting that like MDC1 and BRCA1, Nbs1 also possesses tandem BRCT domains with phosphoprotein binding ability. Structure-based single point mutations in human Nbs1 were evaluated in vivo and revealed that BRCT2 is essential for all MDC1-dependent relocalization of Nbs1 to DNA damage sites, most likely through a direct interaction of Nbs1 tandem BRCT domains with phosphorylated MDC1. (c) 2008 Elsevier Ltd. All rights reserved.

【 授权许可】

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