Yeast Protein Controls Prion Formation

Researchers studying amyloid fibers, plaque-like proteins that form in the brains of individuals with Alzheimer's disease, have found a protein in yeast that can either prevent formation of the fibers under some conditions or dissolve them under others.

Investigators at the Whitehead Institute for Biomedical Research (Cambridge, MA, USA) worked with two yeast proteins, Sup35 and Hsp104. When a critical level of Hsp104 was present in the cell, Sup35 formed into a self-perpetuating fibrous prion-like structure called PSI+. When Hsp104 was either absent or present in high levels, PSI+ did not form. These findings were published May 20, 2004, in the online edition of Science.

While a certain amount of Hsp104 was required for Sup35 to initiate prion formation, high levels caused the fibrous structures to change conformation and become soluble. "These proteins are remarkably stable,” said senior author Dr. Susan Lindquist, director of the Whitehead Institute. "This is the first time that anyone has found anything that can catalytically take apart an amyloid fiber. Given their resilient structure, the fact that a protein can take apart these amyloids is remarkable. It has huge implications for our understanding of the protein folding process in amyloid-related conditions.”




Related Links:
Whitehead Institute for Biomedical Research