Structure-Specific Endonucleases and Genome Stability

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Structure-specific DNA endonucleases are key players in the maintenance of genome integrity. They act as specialized surgical tools for the processing of a wide array of secondary DNA structures generated during important DNA repair and recombination events.

However, cleaving DNA bears its own risks for the cell, opening windows of opportunity for the occurrence of potentially dangerous chromosome alterations and rearrangements at the origin of cancer development. The action of structure-specific endonucleases must therefore be tightly coordinated with downstream events that will ensure that the integrity of the chromosome is fully restored.

An additional challenge for the cell stems from the fact that many structure-specific endonucleases act on junctions between double-strand and single-strand DNA, independently of the nucleotidic sequence. These junctions are found in many structures generated during DNA replication, repair, recombination and transcription. Therefore, in addition to controlling these enzymes in the context of their physiological reaction, the cell must ensure that they do not act randomly on structures generated during other DNA transactions. Despite their fundamental nature, the mechanisms that control structure-specific endonucleases still remain poorly understood.

To tackle this fundamental question we are carrying out a detailed analysis of the regulation of structure-specific DNA endonucleases throughout the cell-cycle and in response to genotoxic stress. Our studies are carried out in both human cells and in the fission yeast Schizosaccharomyces pombe.S. pombe constitutes a proven model system for the analysis and understanding of evolutionary conserved processes involved in genome maintenance in higher eukaryotes.

The remarkable investigational potential that S. pombe has to offer allows us to combine genetic and cellular analysis with proteomic and biochemical studies. Particular attention is placed on the development of in vitro assays to dissect the molecular mechanisms underlying the control of structure-specific endonucleases.

Results from our investigations in yeast provide a platform to extend our analyses to mammalian cells, with a constant focus on assessing their relevance in the context of cancer biology.