Prion


This is my extra credit assignment.

DOI:1 Scouras, Alexander D., and Valerie Daggett. "Species Variation in PrPSc Protofibril Models." Journal of Materials Science 43.10 (2008): 3625-637. Web.

DOI:2 Yam, Alice Y., Carol Man Gao, Xuemei Wang, Ping Wu, and David Peretz. "The Octarepeat Region of the Prion Protein Is Conformationally Altered in PrPSc." Ed. Jiyan Ma. PLoS ONE 5.2 (2010): E9316. Web.

DOI:3 Riesner, D. "Biochemistry and Structure of PrPC and PrPSc." British Medical Bulletin 66.1 (2003): 21-33. Web.


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PrPC (Left)and PrPSc (Right) structures (1)
  • PrPC is the normal form and PrPSc is the infectious form of the protein.(1)
  • The misfolding of the Prp prion protein is the cause of Bovine Spongiform Encephalopathy, also known as Mad Cow Disease.(1)
  • PrPSc can misfold randomly, making the disease difficult to prevent. However foreign PrPSc can also infect the bovine and change the
    PrPC to the corrupt form.(1)
  • PrPSc has two extra strands (red and green) and are labeled E1 and E4 respectively. Also, a-sheets are formed in addition to the a-helices and b-sheets.(1)
  • E-1 Strand docks onto an existing b-sheet and then the E-4 strand elongates.(1)
  • The insertion and expansion of octapeptide sequences helps to propagate the prions by accelerating to conversion of PrPC to PrPSc.(2)
  • Changing from PrPC to PrPSc decreases the prevalence of a-helices from 43%-20%, and increases b-sheets to 34%. These changes make PrPSc a more thermodynamically stable molecule, contributing to its resiliency. It is not known exactly why PrPC does not convert to the more stable PrPSc more often, being that PrPSc is more stable. It is suggested that the anchoring of PrPC in a lipid membrane protects it from spontaneous conformational changes.(3)
  • PrPSc is much more difficult to digest or degrade. Trypsin almost completely digests PrPC and barely digests PrPSc.(2)