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Gillard, N ; Goffinont, S ; Bure, C ; Davidkova, M ; Maurizot, JC ; Cadene, M ; Spotheim-Maurizot, M

Radiation-induced oxidative damage to the DNA-binding domain of the lactose repressor

Biochemical Journal 403 463-472 Part 3

par Administrateur - publié le

Abstract :

Understanding the cellular effects of radiation-induced oxidation requires the unravelling of key molecular events, particularly damage to proteins with important cellular functions. The Escherichia coli lactose operon is a classical model of gene regulation systems. Its functional mechanism involves the specific binding of a protein, the repressor, to a specific DNA sequence, the operator. We have shown previously that upon irradiation with gamma-rays in solution, the repressor loses its ability to bind the operator. Water radiolysis generates hydroxyl radicals (CH radicals)which attack the protein. Damage of the repressor DNA-binding domain, called the headpiece, is most likely to be responsible of this loss of function. Using CD, fluorescence spectroscopy and a combination of proteolytic cleavage with MS, we have examined the state of the irradiated headpiece.