The yeast prion protein Ure2: insights into the mechanism of amyloid formation

2011 ◽  
Vol 39 (5) ◽  
pp. 1359-1364 ◽  
Author(s):  
Li-Jun Chen ◽  
Elizabeth B. Sawyer ◽  
Sarah Perrett
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Conformational Change ◽  
Nitrogen Metabolism ◽  
Prion Protein ◽  
Molecular Chaperones ◽  
Fibril Formation ◽  
Regulatory Function ◽  
Amyloid Formation ◽  
Yeast Prion

Ure2, a regulator of nitrogen metabolism, is the protein determinant of the [URE3] prion state in Saccharomyces cerevisiae. Upon conversion into the prion form, Ure2 undergoes a heritable conformational change to an amyloid-like aggregated state and loses its regulatory function. A number of molecular chaperones have been found to affect the prion properties of Ure2. The studies carried out in our laboratory have been aimed at elucidating the structure of Ure2 fibrils, the mechanism of amyloid formation and the effect of chaperones on the fibril formation of Ure2.

scholarly journals Specificity of Class II Hsp40 Sis1 in Maintenance of Yeast Prion [RNQ +]

2003 ◽  
Vol 14 (3) ◽  
pp. 1172-1181 ◽  
Author(s):  
Nelson Lopez ◽  
Rebecca Aron ◽  
Elizabeth A. Craig
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Molecular Chaperones ◽  
Mammalian Cells ◽  
Single Amino Acid ◽  
Yeast Prion ◽  
Rich Region ◽  
F Region ◽  
Methionine Residues ◽  
Hsp 40

Sis1 and Ydj1, functionally distinct heat shock protein (Hsp)40 molecular chaperones of the yeast cytosol, are homologs of Hdj1 and Hdj2 of mammalian cells, respectively. Sis1 is necessary for propagation of the Saccharomyces cerevisiae prion [RNQ + ]; Ydj1 is not. The ability to function in [RNQ + ] maintenance has been conserved, because Hdj1 can function to maintain Rnq1 in an aggregated form in place of Sis1, but Hdj2 cannot. An extended glycine-rich region of Sis1, composed of a region rich in phenylalanine residues (G/F) and another rich in methionine residues (G/M), is critical for prion maintenance. Single amino acid alterations in a short stretch of amino acids of the G/F region of Sis1 that are absent in the otherwise highly conserved G/F region of Ydj1 cause defects in prion maintenance. However, there is some functional redundancy within the glycine-rich regions of Sis1, because a deletion of the adjacent glycine/methionine (G/M) region was somewhat defective in propagation of [RNQ + ] as well. These results are consistent with a model in which the glycine-rich regions of Hsp40s contain specific determinants of function manifested through interaction with Hsp70s.

scholarly journals Conformational change, aggregation and fibril formation induced by detergent treatments of cellular prion protein

2008 ◽  
Vol 79 (3) ◽  
pp. 669-678 ◽  
Author(s):  
Liang-Wen Xiong ◽  
Lynne D. Raymond ◽  
Stanley F. Hayes ◽  
Gregory J. Raymond ◽  
Byron Caughey
Keyword(s):  
Conformational Change ◽  
Prion Protein ◽  
Fibril Formation ◽  
Cellular Prion Protein

scholarly journals The Hofmeister effect on amyloid formation using yeast prion protein

2009 ◽  
Vol 19 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Victor Yeh ◽  
James M. Broering ◽  
Andrey Romanyuk ◽  
Buxin Chen ◽  
Yury O. Chernoff ◽  
...  
Keyword(s):  
Prion Protein ◽  
Amyloid Formation ◽  
Yeast Prion ◽  
Hofmeister Effect

scholarly journals Impact of Amyloid Polymorphism on Prion-Chaperone Interactions in Yeast

Viruses ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 349 ◽  
Author(s):  
Andrea N. Killian ◽  
Sarah C. Miller ◽  
Justin K. Hines
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Chaperones ◽  
Chaperone Proteins ◽  
Yeast Prion ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Elements ◽  
Yeast Prions ◽  
Amyloid Aggregates ◽  
Structural Differences ◽  
Chaperone Interactions

Yeast prions are protein-based genetic elements found in the baker’s yeast Saccharomyces cerevisiae, most of which are amyloid aggregates that propagate by fragmentation and spreading of small, self-templating pieces called propagons. Fragmentation is carried out by molecular chaperones, specifically Hsp104, Hsp70, and Hsp40. Like other amyloid-forming proteins, amyloid-based yeast prions exhibit structural polymorphisms, termed “strains” in mammalian systems and “variants” in yeast, which demonstrate diverse phenotypes and chaperone requirements for propagation. Here, the known differential interactions between chaperone proteins and yeast prion variants are reviewed, specifically those of the yeast prions [PSI+], [RNQ+]/[PIN+], and [URE3]. For these prions, differences in variant-chaperone interactions (where known) with Hsp104, Hsp70s, Hsp40s, Sse1, and Hsp90 are summarized, as well as some interactions with chaperones of other species expressed in yeast. As amyloid structural differences greatly impact chaperone interactions, understanding and accounting for these variations may be crucial to the study of chaperones and both prion and non-prion amyloids.

Amyloid formation characteristics of GNNQQNY from yeast prion protein Sup35 and its seeding with heterogeneous polypeptides

2017 ◽  
Vol 149 ◽  
pp. 72-79 ◽  
Author(s):  
Mamoru Haratake ◽  
Tohru Takiguchi ◽  
Naho Masuda ◽  
Sakura Yoshida ◽  
Takeshi Fuchigami ◽  
...  
Keyword(s):  
Prion Protein ◽  
Amyloid Formation ◽  
Yeast Prion

Yeast Prion-Protein, Sup35, Fibril Formation Proceeds by Addition and Substraction of Oligomers

ChemBioChem ◽  
2006 ◽  
Vol 7 (5) ◽  
pp. 757-765 ◽  
Author(s):  
Saravanakumar Narayanan ◽  
Stefan Walter ◽  
Bernd Reif
Keyword(s):  
Prion Protein ◽  
Fibril Formation ◽  
Yeast Prion

Heparin induces amyloid formation in cultured human isletss

2007 ◽  
Vol 30 (4) ◽  
pp. 92 ◽  
Author(s):  
K Potter ◽  
K Park
Keyword(s):  
Cell Death ◽  
B Cells ◽  
Islet Transplantation ◽  
Islet Cell ◽  
Human Islets ◽  
Fibril Formation ◽  
Amyloid Formation ◽  
Secretory Product ◽  
Islet Amyloid ◽  
Heparin Sulfate

Background: Pancreatic islet transplantation offers improved glycemic control in type 1 diabetic patients above standard insulin therapy, ideally minimizing macro- and microvascular complications of diabetes mellitus. However success is limited thus far, with fewer than 10% of patients retaining insulin independence at two years post-transplantation. In addition to immune rejection, many non-immune factors may promote long-term graft secretory dysfunction and loss of viable graft mass. One such important non-immune factor may be the formation of islet amyloid, a pathologic lesion of the islet in type 2 diabetes that contributes to the progressive loss of b cells in that disease and that has been shown to form rapidly in human islets transplanted into NOD.scid mice. Amyloid deposits are composed primarily of the b cell secretory product islet amyloid polypeptide (IAPP), are cytotoxic, and develop in environments in which b cells are stressed. Heparin sulfate is used as an anti-coagulant in clinical islet transplantation and to prevent the instant blood-mediated inflammatory reaction (IBMIR), which occurs upon contact between islets and blood and may destroy a substantial proportion of the grafted islet mass. However, heparin is also known to stimulate amyloid fibril formation. Methods: To determine whether heparin may enhance amyloid formation in human islets and contribute to graft failure, we cultured isolated human islets in the presence or absence of heparin sulfate (42 and 420 units/ml) for 2 weeks in 11.1 mM glucose. Results: Histological assessment of sections of cultured islets for the presence of amyloid (by thioflavin S staining) revealed a marked, concentration-dependent increase in amyloid deposition following culture in the presence of heparin. Quantitative analysis of these sections showed that the proportion of islet area comprised of amyloid was increased approximately 2-fold (0.15%±0.12% vs 0.46%±0.15% of islet area) following culture in 42 units/ml heparin, and the proportion of islets in which amyloid was detectable (amyloid prevalence) was also increased (35%±24% vs 68%±10% of islets). At 420 units/ml heparin, the amyloid area was even greater (0.23%±0.15% vs 0.97%±0.42% of islet area) as was the amyloid prevalence (53%±29% vs 81%±14% of islets). To affirm that heparin can stimulate IAPP fibrillogenesis and enhance IAPP toxicity, we incubated synthetic human IAPP in the presence of heparin and measured amyloid formation in real time by thioflavin T fluorescence, and cell toxicity by Alamar blue viability assay in transformed rat (INS-1) ß-cell cultures. Heparin stimulated IAPP fibril formation and increased death of INS-1 cells exposed to IAPP (78.2%±10.9% vs 51.8%±12.2% of control viability), suggesting that heparin stimulates IAPP aggregation and toxicity. Remarkably, preliminary assessment of human islets cultured in heparin did not show increased islet cell death by TUNEL staining or loss of insulin immunostaining. Conclusion: In summary, heparin increases amyloid formation in cultured human islets. Although our preliminary data does not suggest that heparin-induced amyloid formation contributes to islet cell death, we speculate that heparin-induced amyloid formation may contribute to graft dysfunction and that caution should be used in the clinical application of this drug in islet transplantation.

Sign in / Sign up

Export Citation Format

Share Document