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Fungal prion : ウィキペディア英語版 | Fungal prion
A fungal prion is a prion that infects fungal hosts. Fungal prions are naturally occurring proteins that can switch between multiple, structurally distinct conformations, at least one of which is self-propagating and transmissible to other prions. This transmission of protein state represents an epigenetic phenomenon where information is encoded in the protein structure itself, instead of in nucleic acids. Several prion-forming proteins have been identified in fungi, primarily in the yeast ''Saccharomyces cerevisiae''. These fungal prions are generally considered benign, and in some cases even confer a selectable advantage to the organism. Fungal prions have provided a model for the understanding of disease-forming mammalian prions. Study of fungal prions has led to a characterisation of the sequence features and mechanisms that enable prion domains to switch between functional and amyloid-forming states. ==Sequence Features== Prions are formed by portable, transmissible prion domains that are enriched in asparagine, glutamine, tyrosine and glycine residues. When a reporter protein is fused with a prion domain, it forms a chimeric protein that demonstrates the conformational switching that is characteristic of prions. Meanwhile, removing this prion domain prevents prionogenesis. This suggests that these prion domains are, in fact, portable and are the sole initiatior of prionogenesis. This supports the protein-only hypothesis. A recent study of candidate prion domains in ''S. cerevisiae'' found several specific sequence features that were common to proteins showing aggregation and self-templating properties. For example, proteins that aggregated had candidate prion domains that were more highly enriched in asparagine, while non-aggregating domains where more highly enriched in glutamine and charged peptides. There was also evidence that the spacing of charged peptides that prevent amyloid formation, such as proline, is important in prionogenesis. This discovery of sequence specificity was a departure from previous work that had suggested that the only determining factor in prionogenesis was the overall distribution of peptides.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Fungal prion」の詳細全文を読む
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