Michler's hydrol blue elucidates structural differences in prion strains
Journal article, 2020

Yeast prions provide self-templating protein-based mechanisms of inheritance whose conformational changes lead to the acquisition of diverse new phenotypes. The best studied of these is the prion domain (NM) of Sup35, which forms an amyloid that can adopt several distinct conformations (strains) that confer distinct phenotypes when introduced into cells that do not carry the prion. Classic dyes, such as thioflavin T and Congo red, exhibit large increases in fluorescence when bound to amyloids, but these dyes are not sensitive to local structural differences that distinguish amyloid strains. Here we describe the use of Michler's hydrol blue (MHB) to investigate fibrils formed by the weak and strong prion fibrils of Sup35NM and find that MHB differentiates between these two polymorphs. Quantum mechanical time-dependent density functional theory (TDDFT) calculations indicate that the fluorescence properties of amyloid-bound MHB can be correlated to the change of binding site polarity and that a tyrosine to phenylalanine substitution at a binding site could be detected. Through the use of site-specific mutants, we demonstrate that MHB is a site-specific environmentally sensitive probe that can provide structural details about amyloid fibrils and their polymorphs.

Fluorescence spectroscopy


Amyloid dye

Amyloid fibril



Yiling Xiao

UT Southwestern Medical Center

Sandra Rocha

Chalmers, Biology and Biological Engineering, Chemical Biology

Catherine Kitts

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Anna Reymer

University of Gothenburg

Tamas Beke-Somfai

Hungarian Academy of Sciences

K. K. Frederick

UT Southwestern Medical Center

Bengt Nordén

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Proceedings of the National Academy of Sciences of the United States of America

0027-8424 (ISSN) 1091-6490 (eISSN)

Vol. 117 47 29677-29683

Subject Categories

Biochemistry and Molecular Biology


Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)





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