Figure 1
Conformational differences between the apo- and the holo-forms of the Cv-ATA, represented in pink and blue, respectively. The four variability regions are organized as a 3D interlock at the dimer interface of the holo-Cv-ATA (panel a). In each interlock the interfacial loop and the outer loop belonging to one monomer (shown in a lighter blue and indicated with *) are sandwiched between the PLP-K288 moiety and the N-terminal domain of the neighboring monomer (shown in a darker shade of blue). The superposition of the apo- and holo-Cv-ATA 3D structures represented as full surfaces (panel b) show that, upon PLP loss and structural rearrangement, the reorganization of the four variability regions results in significant alterations of the dimer interface. In each of the two monomers the “holo- to apo-” conformational changes consist of i) the disordering of the N-terminal domain; ii) the refolding of the interfacial loop away from the active site; iii) the rigid-body swing of the outer loop towards the bulk solvent and iv) the wide swing of the K288 side chain from a “forward” to a “backward” conformation, which also requires a deformation of the protein backbone (panels c and d).
