Initiation of DNA recombination/repair in the thermophilic archaeon Sulfolobus acidocaldarius

• Applicant: Dr. Achim Quaiser
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2004 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5426140

DNA double-strand breaks (DSBs) are highly cytotoxic and mutagenic. In eukaryotes, two proteins, Mre11 and Rad50 play a major role in DSBs recombination/repair. In particular, these proteins are involved in the maturation of DSBs during homologous recombination which requires 3' overhangs for recombinases. However, their in vitro activities cannot explain this maturation mechanism suggesting the existence of additional partners. In thermophilic archaea homologs of Mre11 and Rad50 are organised in an operon-like structure, together with two genes encoding a nuclease and a helicase. The nuclease (NurA) exhibits 5'-3' exonuclease activity, indicating that it could be essential for the production of the 3' overhangs (Constantinesco et al., 2002). I'm interested in the design of an in vitro system for DSBs maturation by the Rad50-Mre11 pathway. In the proposed study I will analyse the interactions between the four proteins Mre11, Rad50, NurA and HP4 and investigate the activities of the proteins as well as of the potential complexes. Subsequently I will identify additional proteins binding to the complexes using crude protein extracts from Sulfolobus and specific antibodies. In addition, I will initiate the study of in vivo functions using recently developed genetic tools for Sulfolobus. Together this should lead to comprehensive model of the initation step of DNA recombination/repair in archaea.

• DFG Programme: Research Fellowships
• International Connection: France
• Cooperation Partner: Professor Dr. Patrick Forterre