Investigation of the effect of glycosylation on human prion protein by molecular dynamics.

Prion protein conformational isomerization, PrP(C)-->PrP(Sc), has been attributed as the cause of TSE diseases such as mad-cow disease. The mechanism of such isomerization, however, is little known due the experimental difficulties in studying the scrapie form. Among factors that affect PrP isomerization, the role which glycosylation plays remains vague. The number of innumerous glycan species, together with their high flexibility, leads to ineffective structural characterization. In this research, we studied the effect of chitobiose glycosylation on human PrP, in both monomeric (huPrP(mono)) and dimeric (huPrP(dimer)) forms, by molecular dynamics (MD) simulations. Our results show that this glycosylation has minimal impact on the structure of huPrP(mono). However, it affects the secondary structure of dimeric protein. An additional beta-sheet strand is found while the glycosylation is absent in the huPrP(dimer). Comparatively, when the protein is glycosylated with chitobiose, such beta-sheet addition is not observed.