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Culard, F ; Gervais, A ; de Vuyst, G ; Spotheim-Maurizot, M ; Charlier, M

Response of a DNA-binding protein to radiation-induced oxidative stress

Journal of Molecular Biology 328 (5) 1185-1195

par Administrateur - publié le

Abstract :

The DNA-binding protein MC1 is a chromosomal protein extracted from the archaebacterium. Methanosarcina sp. CHT155. It binds any DNA, and exhibits an enhanced affinity for some short sequences and structures (circles, cruciform DNA). Moreover, the protein bends DNA strongly at the binding site. MC1 was submitted to oxidative stress through gamma-ray irradiation. In our experimental conditions, damage is essentially due to hydroxyl radicals issued from water radiolysis. Upon irradiation, the regular complex between MCl and DNA disappears, while a new complex appears. In the new complex, the protein loses its ability to recognise preferential sequences and DNA circles, and bends DNA less strongly than in the regular one. The new complex disappears and the protein becomes totally inactivated by high doses.