Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

Stéphane Goffinont (1) , Marie Davídková (2) , Mélanie Spotheim-Maurizot (1)

1 CBM - Centre de biophysique moléculaire
2 Department of Radiation Dosimetry

The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dinners. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro gamma-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

Mots clés: DNA; Radiation; Tetramer; Dimer; Lactose repressor; LAC REPRESSOR; CIRCULAR-DICHROISM; OPERATOR; PROTEIN; DAMAGE; OXIDATION; COMPLEXES; DOMAIN; SYSTEM

Stéphane Goffinont, Marie Davídková, Mélanie Spotheim-Maurizot. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor. Biochemical and Biophysical Research Communications, 2009, 386 (2), pp.300-304. ⟨10.1016/j.bbrc.2009.06.012⟩. ⟨hal-00522426⟩