Currently, prion phenomena have been detected in various organisms, in addition to mammals affected by transmissible spongiform encephalopathies. In the budding yeast Saccharomyces cerevisiae, various proteins have prion properties and adopt atypical phenotypes as genetic elements, such as the Sup35 and Ure2 proteins, corresponding to the [PSI+] and [URE3] phenotypes, respectively. Each yeast prion protein has a prion-forming region rich in glutamines and/or asparagines, and can form amyloid fibrils in its prion conformation. Studies on yeast prions have revealed that the amyloid fibrils play critical roles in the life cycle of the yeast prion. First, the amyloid fibril binds the normal prion protein and catalyzes a structural conversion into the abnormal form, the key event of the prion phenomenon. Second, the amyloid fibril is related to the strain differences of the prion phenotypes, by its substructural differences. Third, the number of prion elements multiplies by the fragmentation of amyloid fibrils, which is mediated by a chaperone system in which Hsp104 plays a central role, and the prion elements are distributed to the daughter cells during cell division. Moreover, heterologous prion-prion communications may occur, probably by cross-seeding of amyloid fibrils among different prion proteins in the same yeast cell. Findings achieved by yeast prion studies are making great contributions toward understanding the characteristics of amyloid fibrils and prions.
Protein & Peptide Letters publishes short papers in all important aspects of protein and peptide research, including structural studies, recombinant expression, function, synthesis, enzymology, immunology, molecular modeling, drug design etc. Manuscripts must have a significant element of novelty, timeliness and urgency that merit rapid publication. Reports of crystallisation, and preliminary structure determinations of biologically important proteins are acceptable. Purely theoretical papers are also acceptable provided they provide new insight into the principles of protein/peptide structure and function.