Investigation of the Mutagenic Potential of Naturally Occurring Oxidized DNA Nucleobase Derivatives

The integrity of DNA in living organisms is permanently threatened by many endogenous and exogenous factors. Damages can lead to cell death and serious diseases and have to be repaired by the organism. The focus of this thesis is the investigation of the ability of high (Bst Pol I, Klenow fragment exo-) and low fidelity polymerases (Pol kappa, Pol eta) to insert and bypass several oxidatively-derived purine-lesions, such as 8-oxopurines (8-oxodA, 8-oxodG) and formamidopyrimidines (FaPydA, FaPydG), but also guanine-derived imidazolone (dIz) and its further degradation products oxazolone and guanidinoformimine. In order to support the biochemical data and to reveal the replication mechanism of a high fidelity polymerase with FaPy-lesions we performed co-crystallization studies with Bst Pol I. After the discovery that oxidative modifications of the base methylcytosine (mC) occur naturally within the genome and play a key role during cellular development we sought to address the question of their mutagenic potential.