Nucleotide excision repair (NER) in higher organisms repair massive DNA 
abrasions caused by ultraviolet rays, and various mutagens, where Xeroderma 
pigmentosum group A (XPA) protein is known to be involved in damage recognition 
step. Any mutations in XPA cause classical Xeroderma pigmentosum disease. The 
extent to which XPA is required in the NER is still unclear. Here, we present 
the comparative study on the structural and conformational changes in globular 
DNA binding domain of XPA98-210 in DNA bound and DNA free state. Atomistic 
molecular dynamics simulation was carried out for both XPA98-210 systems using 
AMBER force fields. We observed that XPA98-210 in presence of damaged DNA 
exhibited more structural changes compared to XPA98-210 in its free form. When 
XPA is in contact with DNA, we found marked stability of the complex due to the 
formation of characteristic longer antiparallel β-sheets consisting mainly 
lysine residues.