This special session will open the conference for two reasons. First, NER has brought the DNA repair field to the attention of the general scientific public with the discovery of a link between UV damage repair defects and Xeroderma pigmentosum. Second, the field has now reached a stage where the repair system can be reconstituted from its individual purified recombinant components (Wood). This tour de force will be reviewed by the speakers, who all played key parts in its evolution; from the beginnings of cloning by complementation (Bootsma) through the development of a yeast (Friedberg) and in vitro (Wood) model systems to the discovery of a cross-talk between NER and transcription (Hoeijmakers).

The topic discussed in this section concerns the repair pathway that is of paramount importance in the removal of spontaneous DNA damage, ranging from hydrolytic deamination, through methylation to oxidative damage. The invited speakers have made major contributions to our understanding of this field. The topics discussed will cover the discovery and characterisation of BER enzymes, their mode of action based on crystal structures and role of BER in response to mutagens and stress factors.

This session will help the participants to understand the 3D constraints that dictate replication fidelity. High resolution crystal structures of several polymerases with their respective substrates will be shown. Moreover, exciting new insights into the way these enzymes deal with damaged nucleotides will also be discussed.