1d4u
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INTERACTIONS OF HUMAN NUCLEOTIDE EXCISION REPAIR PROTEIN XPA WITH RPA70 AND DNA: CHEMICAL SHIFT MAPPING AND 15N NMR RELAXATION STUDIES
OverviewOverview
Human XPA is an essential component in the multienzyme nucleotide excision, repair (NER) pathway. The solution structure of the minimal DNA binding, domain of XPA (XPA-MBD: M98-F219) was recently determined [Buchko et al., (1998) Nucleic Acids Res. 26, 2779-2788, Ikegami et al. (1998) Nat., Struct. Biol. 5, 701-706] and shown to consist of a compact zinc-binding, core and a loop-rich C-terminal subdomain connected by a linker sequence., Here, the solution structure of XPA-MBD was further refined using an, entirely new class of restraints based on pseudocontact shifts measured in, cobalt-substituted XPA-MBD. Using this structure, the surface of XPA-MBD, which interacts with DNA and a fragment of the largest subunit of, replication protein A (RPA70 Delta C327: M1-Y326) was determined using, chemical shift mapping. DNA binding in XPA-MBD was highly localized in the, loop-rich subdomain for DNA with or without a lesion [dihydrothymidine, (dhT) or 6-4-thymidine-cytidine (64TC)], or with DNA in single- or, double-stranded form, indicating that the character of the lesion itself, is not the driving force for XPA binding DNA. RPA70 Delta C327 was found, to contact regions in both the zinc-binding and loop-rich subdomains. Some, overlap of the DNA and RPA70 Delta C327 binding regions was observed in, the loop-rich subdomain, indicating a possible cooperative DNA-binding, mode between XPA and RPA70 Delta C327. To complement the chemical shift, mapping data, the backbone dynamics of free XPA-MBD and XPA-MBD bound to, DNA oligomers containing dhT or 64TC lesions were investigated using 15N, NMR relaxation data. The dynamic analyses for the XPA-MBD complexes with, DNA revealed localized increases and decreases in S2 and an increase in, the global correlation time. Regions of XPA-MBD with the largest increases, in S2 overlapped regions having the largest chemical shifts changes upon, binding DNA, indicating that the loop-rich subdomain becomes more rigid, upon binding DNA. Interestingly, S2 decreased for some residues in the, zinc-binding core upon DNA association, indicating a possible concerted, structural rearrangement on binding DNA.
DiseaseDisease
Known diseases associated with this structure: Xeroderma pigmentosum, group A OMIM:[611153]
About this StructureAbout this Structure
1D4U is a Single protein structure of sequence from Homo sapiens with ZN as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Interactions of human nucleotide excision repair protein XPA with DNA and RPA70 Delta C327: chemical shift mapping and 15N NMR relaxation studies., Buchko GW, Daughdrill GW, de Lorimier R, Rao B K, Isern NG, Lingbeck JM, Taylor JS, Wold MS, Gochin M, Spicer LD, Lowry DF, Kennedy MA, Biochemistry. 1999 Nov 16;38(46):15116-28. PMID:10563794
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