Amyloid fibrils of stefin B show anisotropic properties

Žganec, Matjaž (author), Taler-Verčič, Ajda (author), Muševič, Igor (author), Škarabot, Miha (author), Žerovnik, Eva (author)

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.

• Language: English
• Keywords: nano-sized object, bundle of amyloid fibrils, birefringence, intrinsic fluorescence, label-free imaging
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics; MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 10 str.
• Numbering: Vol. 24, iss. 4, art. 3737
• PID: 20.500.12556/RUL-155598
• UDC: 577.112
• ISSN on article: 1661-6596
• DOI: 10.3390/ijms24043737
• COBISS.SI-ID: 142086659
• Publication date in RUL: 08.04.2024

Record is a part of a journal

• Title: International journal of molecular sciences
• Shortened title: Int. j. mol. sci.
• Publisher: MDPI
• ISSN: 1661-6596
• COBISS.SI-ID: 36217605

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: delci nanovelikosti, skupki amiloidnih fibril, dvolomnost, intrinzična fluorescenca, slikanje brez označevanja

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: J7-4050
• Name: Oligomeri amiloidogenih proteinov od a do ž; biofizikalne lastnosti, struktura, funkcija in medsebojne interakcije

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0140
• Name: Proteoliza in njena regulacija pri zdravju in boleznih