Figure 3. The structure of the SorT/SorU electron transfer complex.
(A) The asymmetric unit from the crystal structure of the SorT/SorU complex contains the functional electron transfer complex. The SorU/SorT2/SorU complex is revealed by the application of crystallographic symmetry operators. The positions of the redox active molybdenum (SorT) and heme c (SorU) cofactors are indicated. (B) Two views of an overlay of the SorU/SorT2/SorU crystal structure with the averaged and filtered dummy atom model from 10 ab initio reconstructions as revealed by SAXS analyses. (C) ‘Open-book unfolding’ of SorT/SorU complex (SorT is shown in blue, SorU in red) indicating the ‘footprint’ of interfacing residues from each protein. (D) The same view as Panel C, showing the charge complementarity of the SorT/SorU interface (areas of positive charge in blue, negative charge in red and neutral in white).