Fig. 5: Structural homology of HEX-1 proteins.

a Superposition of the MgHEX-1 3D ED micro- (blue) and nano- (red) volume structures with the MgHEX-1 SSX structure (yellow), all in backbone representation. The only region showing major structural differences with RMSDs above 1.0 Å is highlighted by the red box. b Cartoon representation of the NcHEX-1 reference structure (PDB 1KHI; green) purified from E. coli and crystallized by sitting-drop vapour diffusion superimposed with that of MgHEX-1 crystallized in insect cells and obtained from microvolume 3D ED (blue). The average RMSD is 0.45 Å for 123 equivalent C atoms. c 2Fo-Fc map (grey, contoured at 1σ) of most deviant residues 89–94 (red box in (b)) of the MgHEX-1 3D ED microvolume structure (green) in stick representation superimposed with the corresponding residues in the NcHEX-1 structure (blue). The side chains of residues Ser90 and Thr93 fit well into the 2Fo-Fc map calculated for MgHEX-1, in contrast to the corresponding Phe and Asn residues of NcHEX-1, ruling out phase bias imposed by phase determination applying the molecular replacement approach with a similar reference structure as the search model.