The Architecture of Molecular Complexes Involved in UV-damage Recognition

The work presented in this thesis aims to contribute to understanding of the molecular mechanisms that underlie UV-damage recognition. If not recognized and repaired, damage can result in DNA mutation, which might result in uncontrolled cell growth (cancer) or cell death. The biological relevance of UV-damage repair is emphasised by the severe clinical features associated with three rare autosomal-recessive inherited syndromes: xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). More specifically, it analyzes the architecture of the protein-DNA complexes formed during the repair reaction. To this purpose, individual protein-DNA complexes were visualized by scanning force microscopy (SFM) (Chapter 3 and 4). Chapter 1 briefly introduces UV-damages and the relevance of UV-damage repair mechanisms. In this chapter we introduce some background important to understand nucleotide excision repair NER, highlighting the roles of every factor involved. In addition, a brief overview of the proteins that are required for damage detection in photoreactivation and NER in humans and Escherichia coli is given. In the Chapter 2 the application of SFM to study the conformation of protein complexes and their functional assemblies on DNA in DNA repair processes, imaging strategies and its challenges are presented.