Unraveling the key to the resistance of canids to prion diseases
A. Structural Cα backbone superposition of Model01 (blue) and Model02 (orange) cartoons (representing the mouse). Both N- and C-term regions are labeled. No significant structural rearrangements between the backbones can be observed. B. Structural Cα backbone superposition of canine prion protein (green) (PDB ID 1XYK) and Model01 (blue) and Model02 (orange) cartoons. Despite some detectable differences, overall folding of the models with respect to dog PrP remains similar. C-E. Local environment of mouse Asn158 (N158) from PDB ID 1XYX (gray) and arrangement of Asp158 (D158) (C) (PDB ID 1XYK- blue), Asp158 (D158) from Model01 (D) (orange) and Asp158 (D158) structure in Model02 (E) (green). All residues are labeled and represented as sticks. N158 from mouse PrP shows a hydrogen bond to M133 stabilizing the Cα backbone. While D158 from Model02 does not establish other interactions, D158 conformer from Model01 exhibits a change leading to the formation of a salt bridge with R135. Analogous hydrogen bond can be observed between N158 and R135 also in mouse PrP but, no similar interaction can be found with surrounding residues in dog PrP.