3shv
From Proteopedia
Crystal structure of human MCPH1 tandem BRCT domains-gamma H2AX complex
Structural highlights
Disease[MCPH1_HUMAN] Premature chromosome condensation with microcephaly and intellectual deficit;Autosomal recessive primary microcephaly. Defects in MCPH1 are the cause of microcephaly primary type 1 (MCPH1) [MIM:251200]; also known as true microcephaly or microcephaly vera. Microcephaly is defined as a head circumference more than 3 standard deviations below the age-related mean. Brain weight is markedly reduced and the cerebral cortex is disproportionately small. Despite this marked reduction in size, the gyral pattern is relatively well preserved, with no major abnormality in cortical architecture. Primary microcephaly is further defined by the absence of other syndromic features or significant neurological deficits. This entity is inherited as autosomal recessive trait.[1] [2] [3] Function[MCPH1_HUMAN] Implicated in chromosome condensation and DNA damage induced cellular responses. May play a role in neurogenesis and regulation of the size of the cerebral cortex.[4] [5] [6] [H2AX_HUMAN] Variant histone H2A which replaces conventional H2A in a subset of nucleosomes. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Required for checkpoint-mediated arrest of cell cycle progression in response to low doses of ionizing radiation and for efficient repair of DNA double strand breaks (DSBs) specifically when modified by C-terminal phosphorylation.[7] [8] [9] [10] Publication Abstract from PubMedMCPH1 is especially important for linking chromatin remodeling to DNA damage response. It contains three BRCT (BRCA1-carboxyl terminal) domains. The N-terminal region directly binds with chromatin remodeling complex SWI-SNF, and the C-terminal BRCT2-BRCT3 domains (tandem BRCT domains) are involved in cellular DNA damage response. The MCPH1 gene associates with evolution of brain size, and its variation can cause primary microcephaly. In this study we solve the crystal structures of MCPH1 natural variant (A761) C-terminal tandem BRCT domains alone as well as in complex with gammaH2AX tail. Compared with other structures of tandem BRCT domains, the most significant differences lie in phosphopeptide binding pocket. Additionally, fluorescence polarization assays demonstrate that MCPH1 tandem BRCT domains show a binding selectivity on pSer +3 and prefer to bind phosphopeptide with free COOH-terminus. Taken together, our research provides new structural insights into BRCT-phosphopeptide recognition mechanism. Specific recognition of phosphorylated tail of H2AX by the tandem BRCT domains of MCPH1 revealed by complex structure.,Shao Z, Li F, Sy SM, Yan W, Zhang Z, Gong D, Wen B, Huen MS, Gong Q, Wu J, Shi Y J Struct Biol. 2011 Dec 1. PMID:22154951[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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