6j44
From Proteopedia
Crystal structure of the redefined DNA-binding domain of human XPA
Structural highlights
Disease[XPA_HUMAN] Defects in XPA are a cause of xeroderma pigmentosum complementation group A (XP-A) [MIM:278700]; also known as xeroderma pigmentosum type 1 (XP1). XP-A is a rare human autosomal recessive disease characterized by solar sensitivity, high predisposition for developing cancers on areas exposed to sunlight and, in some cases, neurological abnormalities. Group A patients show the most severe skin symptoms and progressive neurological disorders.[1] [2] [3] Function[XPA_HUMAN] Involved in DNA excision repair. Initiates repair by binding to damaged sites with various affinities, depending on the photoproduct and the transcriptional state of the region. Required for UV-induced CHEK1 phosphorylation and the recruitment of CEP164 to cyclobutane pyrimidine dimmers (CPD), sites of DNA damage after UV irradiation.[4] Publication Abstract from PubMedXPA (xeroderma pigmentosum complementation group A), a key scaffold protein in nucleotide excision repair (NER) pathway, is important in DNA damage verification and repair proteins recruitment. Earlier studies had mapped the minimal DNA-binding domain (MBD) of XPA to a region corresponding to residues 98-219. However, recent studies indicated that the region involving residues 98-239 is the redefined DNA-binding domain (DBD), which binds to DNA substrates with a much higher binding affinity than MBD and possesses a nearly identical binding affinity to the full-length XPA protein. However, the structure of the redefined DBD domain of XPA (XPA-DBD) remains to be investigated. Here, we present the crystal structure of XPA-DBD at 2.06A resolution. Structure of the C-terminal region of XPA has been extended by 21 residues (Arg211-Arg231) as compared with previously reported MBD structures. The structure reveals that the C-terminal extension (Arg211-Arg231) is folded as an alpha-helix with multiple basic residues. The positively charged surface formed in the last C-terminal helix suggests its critical role in DNA binding. Further structural analysis demonstrates that the last C-terminal region (Asp217-Thr239) of XPA-DBD might undergo a conformational change to directly bind to the DNA substrates. This study provides a structural basis for understanding the possible mechanism of enhanced DNA-binding affinity of XPA-DBD. Structural characterization of the redefined DNA-binding domain of human XPA.,Lian FM, Yang X, Yang W, Jiang YL, Qian C Biochem Biophys Res Commun. 2019 May 12. pii: S0006-291X(19)30918-0. doi:, 10.1016/j.bbrc.2019.05.050. PMID:31092331[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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