Amyloid fibers are protein aggregates associated with numerous neurodegenerative diseases, including Parkinson's disease, for which there are no effective treatments.

However, on the flip side, the fibers can also play beneficial, protective roles. In yeast, they are associated with increased survival and the evolution of new traits. In humans, they form biological nanostructures to house pigments and other molecules and may also be central to long-term memory formation and storage. Amyloid fibers are among the most stable protein-based structures in nature, and so when they are detrimental, as in Parkinson's disease, they are notoriously difficult for cells to break down.

In a new study published in PLoS Biology this week, James Shorter, PhD, assistant professor of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, and colleagues address an urgent need to find ways to promote beneficial amyloid fiber assembly or to reverse its pathogenic assembly, at will.

In the paper, Shorter and colleagues define the mechanisms by which small heat-shock proteins (hsp) collaborate with other molecular chaperones to regulate the assembly and disassembly of a beneficial yeast prion (an amyloid that can spread between individuals).

Yeast harbor a declumping protein called Hsp104, which rapidly disassembles amyloid fibers, and this activity is greatly enhanced by small heat shock proteins. Humans and other animals, however, lack Hsp104, and so the puzzle has always been: Can human cells also disassemble these exceptionally stable amyloid fibers?

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