The aim of the project is to conduct in vivo, in vitro and in silico studies of the substrate specificity of AidB dehydrogenase against the by-products rising in AlkB dioxygenase repair reaction and AlkB and AidB cooperative interaction in the repair of adducts to DNA and RNA bases. AidB dehydrogenase and AlkB dioxygenase are induced in the E. coli adaptive response to alkylating agents. As a result of direct AlkB removal of base modifications, toxic and mutagenic by-products are formed: formaldehyde, glyoxal or malondialdehyde. Our studies indicate that AlkB is efficiently inhibited in vitro by the side products of the repair reaction. The biological role and substrates of AidB are unknown. It is known that AidB does not repair DNA lesions; its crystallographic structure points to small molecule substrates. This allowed me to formulate the hypothesis that AidB dehydrogenase may be involved in the detoxification of highly reactive by-products generated as a result of AlkB repair and that to prevent their release to the cell, these enzymes can interact directly in the cell homeostasis maintenance.