Peter M. J. Burgers
Our laboratory is studying nuclear DNA replication and repair in the yeast Saccharomyces cerevisiae. Yeast is an ideal eukaryotic organism to study questions relating to control and mechanism of DNA replication both at a genetic and at a biochemical level.
Current efforts focus on the formation of the eukaryotic replisome at replication origins, its architecture, and the mechanisms by which it ensures a high fidelity of DNA synthesis. Specifically, we aim to understand (i) the functions of three distinct DNA polymerases (a, d, and e) at the replication fork; (ii) the mechanisms by which accessory factors associate with these DNA polymerases to form replication-competent complexes at the replication fork; and (iii) how the different replication complexes at the leading strand and at the lagging strand physically interact into a replisome to ensure coordinated DNA replication of the chromosome. These biochemical studies of the interactions between the various proteins and the DNA benefit from the availability of most or all of them in pure form.
Genetic studies are aimed at complementing and extending our biochemical knowledge of the system. Since a large number of the genes encoding the DNA polymerases and their accessory factors have been cloned and characterized, genetic studies which address the above questions mainly involve the isolation of temperature sensitive mutants in replication genes. These mutants will be used to study defects in DNA replication and DNA repair and in the isolation of extragenic suppressors. Suppressor analysis can often give valuable information on the physical interaction of proteins in multipolypeptide complexes, and also lead to the isolation of novel genes involved in DNA replication or its control.