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 PubMed
XPA (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
- ↑ Satokata I, Tanaka K, Okada Y. Molecular basis of group A xeroderma pigmentosum: a missense mutation and two deletions located in a zinc finger consensus sequence of the XPAC gene. Hum Genet. 1992 Mar;88(6):603-7. PMID:1339397
- ↑ Satokata I, Tanaka K, Yuba S, Okada Y. Identification of splicing mutations of the last nucleotides of exons, a nonsense mutation, and a missense mutation of the XPAC gene as causes of group A xeroderma pigmentosum. Mutat Res. 1992 Mar;273(2):203-12. PMID:1372103
- ↑ States JC, McDuffie ER, Myrand SP, McDowell M, Cleaver JE. Distribution of mutations in the human xeroderma pigmentosum group A gene and their relationships to the functional regions of the DNA damage recognition protein. Hum Mutat. 1998;12(2):103-13. PMID:9671271 doi:<103::AID-HUMU5>3.0.CO;2-6 10.1002/(SICI)1098-1004(1998)12:2<103::AID-HUMU5>3.0.CO;2-6
- ↑ Pan YR, Lee EY. UV-dependent interaction between Cep164 and XPA mediates localization of Cep164 at sites of DNA damage and UV sensitivity. Cell Cycle. 2009 Feb 15;8(4):655-64. Epub 2009 Feb 14. PMID:19197159
- ↑ Lian FM, Yang X, Yang W, Jiang YL, Qian C. Structural characterization of the redefined DNA-binding domain of human XPA. Biochem Biophys Res Commun. 2019 May 12. pii: S0006-291X(19)30918-0. doi:, 10.1016/j.bbrc.2019.05.050. PMID:31092331 doi:http://dx.doi.org/10.1016/j.bbrc.2019.05.050
