The Department of Biomedicine

BBB seminar: Elin Moe

Structure/function studies of Base Excision Repair (BER) enzymes from the extremophile bacterium Deinococcus radiodurans

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Elin Moe
The Norwegian Structural Biology Center (NorStruct), University of Tromsø

Deinococcus radiodurans is a gram-positive bacterium that displays an extraordinary resistance to ionising radiation and desiccation. Whereas D. radiodurans tolerates ionising radiation doses of 5000-30000 grays, most other organisms cannot survive doses of above 50 grays. Initial investigations support the view that this extreme resistance to radiation is complex, and most likely determined by a combination of factors such as efficient DNA repair machinery, genome packing and cell structure. In order to investigate the importance of the DNA repair machinery for the radiation resistance phenotype, structural studies of proteins from three major DNA repair pathways, Base Excision Repair (BER), Nucleotide-Excision Repair (NER) and Recombinational Repair (RR), have been initiated as a collaborative project between the Norwegian Structural Biology Centre (NorStruct) at the University of Tromsø and the Macromolecular Crystallography (MX) Group at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The group in Tromsø has focused on the BER pathway, whereas scientists at the ESRF are working on the NER and RR pathways. The genome of D. radiodurans contains an unusually high number of genes encoding BER enzymes, i.e. five uracil-DNA glycosylases, two 3-methyladenine DNA glycosylase II (AlkA) and three Endonuclease III. So far we have determined the three-dimensional structures of four DNA glycosylases, and here we present results from structure/function studies of uracil-DNA glycosylase (UNG), mismatch specific uracil-DNA glycosylase (MUG), one 3-methyladenine DNA glycosylase II (AlkA) and one Endonuclease III. These DNA glycosylases, and other proteins involved in BER, will be used in further studies of protein complexes in D. radiodurans in the FUGE supported project “Protein-protein interactions at atomic levels”. The status and future plans of the project will be presented.

Chair: Ida Helene Steen <ida.steen@bio.uib.no>, Department of Biology