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Nature of cross-seeding barriers of amyloidogenesis

100%

Stępkowski D., Bieniaś J.

2012

vol. 59

issue 2

307-312

The epidemics of bovine spongiform encephalopathy (BSE) several decades ago and present epidemics of chronic wasting disease (CWD) among cervids posed a threat of cross-species infections to humans or other animals. Therefore, the question as to the molecular nature of the species barriers to transmissibility of prion diseases is very important. We approached this problem theoretically, first developing a model of template-monomer interaction based on logical and topological grounds and on experimental data about cross-seeding of PrP 23-144 protein orthologs. Further, we propose that the strength of the cross-seeding barriers is proportional to dissimilarity of key amyloidogenic regions of the proteins. This dissimilarity can be measured by dissimilarity function we propose. Scaled on experimental data, this function predicts if cross-seeding can occur between different variants of PrP23-144. The resemblance of PrP23-144 cross-seeding barriers to the barriers of cross-species transmissibility of prion diseases is discussed. We suggest that a similar theoretical approach could be applied to predicting the occurrence of species barriers of prion diseases at least in part corresponding to the process of multiplication of infectious agent.

Silver ions as em marker of congo red ligation sites in amyloids and amyloid-like aggregates

84%

Rybarska J., Konieczny L., Jagusiak A., Chłopaś K., Zemanek G., Piekarska B., Stopa B., Piwowar P., Woźnicka O., Roterman I.

2017

vol. 64

issue 1

161-169

Congo red (CR) is a known selective amyloid ligand. The focus of our work is identification (by EM imaging) of dye binding sites and their distribution in amyloids and amyloid-like aggregates formed in vitro. In order to produce the required contrast, CR has been indirectly combined with metal via including Titan yellow (TY) by intercalation which exhibits a relatively strong affinity for silver ions. The resulting combined ligand retains its ability to bind to proteins (which it owes to CR) and can easily be detected in EM studies thanks to TY. We have found, however, that in protein aggregates where unfolding is stabilized by aggregation and therefore is irreversible, TY alone may serve as both, the ligand and the metal carrier. The formation of ordered structures in amyloids was studied using IgG light chains with amyloidogenic properties, converted into amyloids by shaking. The resulting EM images were subjected to interpretation on the basis of the authors' earlier research on the CR/light chain complexation process. Our results indicate that dimeric light chains, which are the subject of our study, produce amyloids or amyloid-like complexes with chain-like properties and strong helicalization tendencies. Cursory analysis suggests that the edge polypeptide loops belonging to unstable light chains form intermolecular bridges which promote creation of loose gel deposits, or are otherwise engaged in the swapping processes leading to higher structural ordering.

Amyloidy i prionoidy – czy jest już czas, żeby się obawiać?

84%

Liberski P. P.

Aktualności Neurologiczne

2013

vol. 13

issue 3

230-239

The new era has come to microbiology as we have realized that the unconventional viruses of kuru, Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), scrapie, and bovine spongiform encephalopathy (BSE) are infectious amyloid proteins and that these transmissible spongiform dementias are brain amyloidoses. This quotation from a Nobel laureate, D. Carleton Gajdusek, illustrates the best the content of this paper. Amyloid is a generic term, which embraces the fibrillary cross-β-sheet quaternary structure of any protein. All amyloids, irrespective of their amino acid sequences, are formed through nucleation/polymerization reactions in which oligomeric structures (small aggregates) composed of a limited number of a given protein moiety (a seed) nucleates other moieties. As a result, the β-pleated secondary structure predominates. Such proteins are called “prionoids” as opposed to “real” prions, which are infectious, or transmissible, in a microbiological sense; they spread between individuals and cause macro-epidemics, such as kuru, BSE and iatrogenic CJD. In this review, prions and prionoids, and their inter-relatedness, will be discussed.

Nadeszła nowa era mikrobiologii, kiedy zrozumieliśmy, że niekonwencjonalne wirusy kuru, choroby Creutzfeldta--Jakoba (CJD) i zespołu [obecnie „choroby”] Gerstmanna-Sträusslera-Scheinkera (GSS), scrapie, encefalopatii gąbczastej bydła (BSE) są infekcyjnymi białkami amyloidowymi i że pasażowalne encefalopatie gąbczaste są amyloidozami mózgu. Ten cytat z wypowiedzi laureata Nagrody Nobla D. Carletona Gajduska znakomicie ilustruje całość zagadnienia. Amyloid to nazwa ogólna określająca włókienkową czwartorzędową strukturę białka. Wszystkie amyloidy, niezależnie od sekwencji aminokwasów tworzących je białek, tworzą się w wyniku reakcji nukleacji/polimeryzacji, w której agregaty (oligomery), składające się z niewielkiej liczby cząsteczek białka (jądro, seed), nukleują cząsteczki białka prekursorowego, co prowadzi do zmiany konformacji przestrzennej w kierunku harmonijki-β. Choroby wywołane przez takie białka nazywa się prionoidami. „Prawdziwe” priony różnią się zasadniczo od wszystkich innych prionoidów − priony są zakaźnie w sensie mikrobiologicznym, szerzą się między osobnikami, wywołując makroepidemie, takie jak kuru, vCJD, BSE i jatrogenne przypadki CJD. W niniejszym artykule zostaną omówione podstawowe prionoidy − choroby Alzheimera i Parkinsona – oraz relacja łącząca je z chorobami prionowymi.

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2 Acta Biochimica Polonica

1 Aktualności Neurologiczne

1 2017

1 2013

1 2012

1 Bieniaś J.

1 Chłopaś K.

1 Jagusiak A.

1 Konieczny L.

1 Liberski P. P.

1 Piekarska B.

1 Piwowar P.

1 Roterman I.

1 Rybarska J.

1 Stopa B.

1 Stępkowski D.

1 Woźnicka O.

1 Zemanek G.

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Nature of cross-seeding barriers of amyloidogenesis

Silver ions as em marker of congo red ligation sites in amyloids and amyloid-like aggregates

Amyloidy i prionoidy – czy jest już czas, żeby się obawiać?