Upon agitation, aggregates of the potent Sc4 prion form break apart (left), but a less potent form remains intact (right).

WEISSMAN/MACMILLAN

Prion proteins with the same amino acid sequence but different biophysical and biochemical structures show different pathological severities. A study of a yeast prion model, by Motomasa Tanaka, Jonathan Weissman, and colleagues (University of California, San Francisco, CA) reveals that a prion's power is determined by aggregate stability—or, rather, lack of it.

Prions replicate by recruiting their normally folded counterparts into large aggregate fibers, which then break up to form new prion particles, capable of recruiting and converting further normal forms. A shortened version of the yeast protein Sup35, called SupNM, can misfold into various prion forms. These forms seed aggregates that result in phenotypes of reproducibly different strengths.

To investigate the basis for this difference, Weisman's team looked at how fast the SupNM-derived...

The Rockefeller University Press
2006
The Rockefeller University Press
2006
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