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The discovery boosts basic understanding of prion infections, and could provide scientists with new ideas for designing drugs that discourage or prevent prion seeding, said the study's senior author Jonathan Weissman, a Howard Hughes Medical Institute investigator at the University of California, San Francisco (UCSF).

Weissman and colleagues from UCSF reported their findings on June 28, 2006, in an advance online publication in Nature.

The scientists studied yeast prions, which are similar to mammalian prions in that they act as infectious proteins. In recent years, mammalian prions have gained increasing notoriety for their roles in such fatal brain-destroying human diseases as Creutzfeldt-Jakob disease and kuru, and in the animal diseases, bovine spongiform encephalopathy ("mad cow" disease) and scrapie.

Yeast and mammalian prions are proteins that transmit their unique characteristics via interactions in which an abnormally shaped prion protein influences a normal protein to assume an abnormal shape. In mammalian prion infections, these abnormal shapes trigger protein clumping that can kill brain cells. In yeast cells, the insoluble prion protein is not deadly; it merely alters a cell's metabolism. Prions propagate themselves by division of the insoluble clumps to create "seeds" that can continue to grow by causing aggregation of more proteins.

In earlier studies, Weissman and his colleagues had discovered that the same prion can exist in different strains and have different infectious properties. These strains arise from different misfoldings of the prion protein that result in different conformations.
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Source:Howard Hughes Medical Institute