The evolutionary origin of the prion gene that is responsible for causing diseases such as bovine spongiform encephalopathy (BSE), also known as "mad cow disease" has been uncovered by scientists.
Diseased prion proteins are responsible for the fatal neurodegenerative Creutzfeldt-Jakob disease (CJD) in humans, and BSE, scrapie and chronic wasting disease (CWD) in livestock.
The researchers say that the new study may provide insights into the origins and underlying constraints of the conformational changes associated with prion diseases.
"The prion protein was discovered over twenty years ago and has been studied intensively. Nobody, however, knew its evolutionary origin and much confusion surrounds its physiological function," said principal investigator Gerold Schmitt-Ulms (Centre for Research in Neurodegenerative Diseases; Department of Laboratory Medicine and Pathobiology, U of T)
The team's analysis suggests that the prion gene is descended from the more ancient ZIP family of metal ion transporters.
The members of ZIP protein family are well known for their ability to transport zinc and other metals across cell membranes.
Schmitt-Ulms has found that prion and ZIP proteins contain extensive stretches of similar amino acid sequence.
The researchers next documented that the respective segments within ZIP and prion proteins are computationally predicted to acquire a highly similar three-dimensional structure.
Finally, the team uncovered multiple additional commonalities between ZIP and prion proteins, which led them to conclude these molecules, are evolutionarily related.
The study was published in the online journal PLoS ONE.