Time-resolved structural response to light of the full-length carH protein from Thermus thermophilus

The protein carH associates with the B12 vitamin, (AdoCbl), to form a light-sensitive gene repressor in bacteria. CarH is composed of a chromophore binding domain (CBD) and a DNA binding domain (DBD). In dark state, the protein forms a stable tetramer. Upon light exposure, the H132 residue of carH binds to the cobalt atom and the tetramer eventually dissociates. Little is known about the structural response of carH after light absorption and we aim at filling this gap. To this end, we already used time-resolved wide-angle X-ray scattering (TR-WAXS) at ID09 on the CBD of CarH from T. Thermophilus (TtCBD) (LS-2958). The TtCBD variant do not show teramer dissociation.
Hence, time-resolved WAXS data on the full-length TtcarH could clarify the role of the DBD and the tetramer dissociation in the protein functional dynamics. Moreover, structural model for the intermediates of the full-length carH are still missing as the protein crystal usually do not survive the teramer dissociation.