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Amyloid Fibrils of Stefin B Show Anisotropic Properties

Human stefin B, a member of the cystatin family of cysteine protease inhibitors, tends to form amyloid fibrils under relatively mild conditions, which is why it is used as a model protein to study amyloid fibrillation. Here, we show for the first time that bundles of amyloid fibrils, i.e., helically...

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Autores principales: Žganec, Matjaž, Taler Verčič, Ajda, Muševič, Igor, Škarabot, Miha, Žerovnik, Eva
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9962164/
https://www.ncbi.nlm.nih.gov/pubmed/36835149
http://dx.doi.org/10.3390/ijms24043737
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author Žganec, Matjaž
Taler Verčič, Ajda
Muševič, Igor
Škarabot, Miha
Žerovnik, Eva
author_facet Žganec, Matjaž
Taler Verčič, Ajda
Muševič, Igor
Škarabot, Miha
Žerovnik, Eva
author_sort Žganec, Matjaž
collection PubMed
description Human stefin B, a member of the cystatin family of cysteine protease inhibitors, tends to form amyloid fibrils under relatively mild conditions, which is why it is used as a model protein to study amyloid fibrillation. Here, we show for the first time that bundles of amyloid fibrils, i.e., helically twisted ribbons, formed by human stefin B exhibit birefringence. This physical property is commonly observed in amyloid fibrils when stained with Congo red. However, we show that the fibrils arrange in regular anisotropic arrays and no staining is required. They share this property with anisotropic protein crystals, structured protein arrays such as tubulin and myosin, and other anisotropic elongated materials, such as textile fibres and liquid crystals. In certain macroscopic arrangements of amyloid fibrils, not only birefringence is observed, but also enhanced emission of intrinsic fluorescence, implying a possibility to detect amyloid fibrils with no labels by using optical microscopy. In our case, no enhancement of intrinsic tyrosine fluorescence was observed at 303 nm; instead, an additional fluorescence emission peak appeared at 425 to 430 nm. We believe that both phenomena, birefringence and fluorescence emission in the deep blue, should be further explored with this and other amyloidogenic proteins. This may allow the development of label-free detection methods for amyloid fibrils of different origins.
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spelling pubmed-99621642023-02-26 Amyloid Fibrils of Stefin B Show Anisotropic Properties Žganec, Matjaž Taler Verčič, Ajda Muševič, Igor Škarabot, Miha Žerovnik, Eva Int J Mol Sci Brief Report Human stefin B, a member of the cystatin family of cysteine protease inhibitors, tends to form amyloid fibrils under relatively mild conditions, which is why it is used as a model protein to study amyloid fibrillation. Here, we show for the first time that bundles of amyloid fibrils, i.e., helically twisted ribbons, formed by human stefin B exhibit birefringence. This physical property is commonly observed in amyloid fibrils when stained with Congo red. However, we show that the fibrils arrange in regular anisotropic arrays and no staining is required. They share this property with anisotropic protein crystals, structured protein arrays such as tubulin and myosin, and other anisotropic elongated materials, such as textile fibres and liquid crystals. In certain macroscopic arrangements of amyloid fibrils, not only birefringence is observed, but also enhanced emission of intrinsic fluorescence, implying a possibility to detect amyloid fibrils with no labels by using optical microscopy. In our case, no enhancement of intrinsic tyrosine fluorescence was observed at 303 nm; instead, an additional fluorescence emission peak appeared at 425 to 430 nm. We believe that both phenomena, birefringence and fluorescence emission in the deep blue, should be further explored with this and other amyloidogenic proteins. This may allow the development of label-free detection methods for amyloid fibrils of different origins. MDPI 2023-02-13 /pmc/articles/PMC9962164/ /pubmed/36835149 http://dx.doi.org/10.3390/ijms24043737 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Brief Report
Žganec, Matjaž
Taler Verčič, Ajda
Muševič, Igor
Škarabot, Miha
Žerovnik, Eva
Amyloid Fibrils of Stefin B Show Anisotropic Properties
title Amyloid Fibrils of Stefin B Show Anisotropic Properties
title_full Amyloid Fibrils of Stefin B Show Anisotropic Properties
title_fullStr Amyloid Fibrils of Stefin B Show Anisotropic Properties
title_full_unstemmed Amyloid Fibrils of Stefin B Show Anisotropic Properties
title_short Amyloid Fibrils of Stefin B Show Anisotropic Properties
title_sort amyloid fibrils of stefin b show anisotropic properties
topic Brief Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9962164/
https://www.ncbi.nlm.nih.gov/pubmed/36835149
http://dx.doi.org/10.3390/ijms24043737
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