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Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects

The N-terminal fragment of apolipoprotein A-I (apoA-I), comprising residues 1–83, contains three segments prone to aggregation: residues 14–22, 53–58, and 67–72. We previously demonstrated that residues 14–22 are critical in apoA-I fibril formation while residues 53–58 entropically drove the nucleat...

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Autores principales: Namba, Norihiro, Ohgita, Takashi, Tamagaki-Asahina, Hiroko, Nishitsuji, Kazuchika, Shimanouchi, Toshinori, Sato, Takeshi, Saito, Hiroyuki
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10613298/
https://www.ncbi.nlm.nih.gov/pubmed/37898709
http://dx.doi.org/10.1038/s41598-023-45803-y
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author Namba, Norihiro
Ohgita, Takashi
Tamagaki-Asahina, Hiroko
Nishitsuji, Kazuchika
Shimanouchi, Toshinori
Sato, Takeshi
Saito, Hiroyuki
author_facet Namba, Norihiro
Ohgita, Takashi
Tamagaki-Asahina, Hiroko
Nishitsuji, Kazuchika
Shimanouchi, Toshinori
Sato, Takeshi
Saito, Hiroyuki
author_sort Namba, Norihiro
collection PubMed
description The N-terminal fragment of apolipoprotein A-I (apoA-I), comprising residues 1–83, contains three segments prone to aggregation: residues 14–22, 53–58, and 67–72. We previously demonstrated that residues 14–22 are critical in apoA-I fibril formation while residues 53–58 entropically drove the nucleation process. Here, we investigated the impact of amyloidogenic mutations (Δ60–71/VT, Δ70–72, and F71Y) located around residues 67–72 on fibril formation by the apoA-I 1–83 fragment. Thioflavin T fluorescence assay demonstrated that the Δ60–71/VT mutation significantly enhances both nucleation and fibril elongation rates, whereas the Δ70–72 and F71Y mutations had minimal effects. Circular dichroism measurements and microscopic observations revealed that all variant fragments formed straight fibrils, transitioning from random coils to β-sheet structures. Kinetic analysis demonstrated that primary nucleation is the dominant step in fibril formation, with fibril elongation reaching saturation at high protein concentrations. Thermodynamically, both nucleation and fibril elongation were enthalpically and entropically unfavorable in all apoA-I 1–83 variants, in which the entropic barrier of nucleation was almost eliminated for the Δ60–71/VT variant. Taken together, our results suggest the presence of new aggregation-prone segment in the Δ60–71/VT variant that promotes nucleation through entropic effects.
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spelling pubmed-106132982023-10-30 Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects Namba, Norihiro Ohgita, Takashi Tamagaki-Asahina, Hiroko Nishitsuji, Kazuchika Shimanouchi, Toshinori Sato, Takeshi Saito, Hiroyuki Sci Rep Article The N-terminal fragment of apolipoprotein A-I (apoA-I), comprising residues 1–83, contains three segments prone to aggregation: residues 14–22, 53–58, and 67–72. We previously demonstrated that residues 14–22 are critical in apoA-I fibril formation while residues 53–58 entropically drove the nucleation process. Here, we investigated the impact of amyloidogenic mutations (Δ60–71/VT, Δ70–72, and F71Y) located around residues 67–72 on fibril formation by the apoA-I 1–83 fragment. Thioflavin T fluorescence assay demonstrated that the Δ60–71/VT mutation significantly enhances both nucleation and fibril elongation rates, whereas the Δ70–72 and F71Y mutations had minimal effects. Circular dichroism measurements and microscopic observations revealed that all variant fragments formed straight fibrils, transitioning from random coils to β-sheet structures. Kinetic analysis demonstrated that primary nucleation is the dominant step in fibril formation, with fibril elongation reaching saturation at high protein concentrations. Thermodynamically, both nucleation and fibril elongation were enthalpically and entropically unfavorable in all apoA-I 1–83 variants, in which the entropic barrier of nucleation was almost eliminated for the Δ60–71/VT variant. Taken together, our results suggest the presence of new aggregation-prone segment in the Δ60–71/VT variant that promotes nucleation through entropic effects. Nature Publishing Group UK 2023-10-28 /pmc/articles/PMC10613298/ /pubmed/37898709 http://dx.doi.org/10.1038/s41598-023-45803-y Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Namba, Norihiro
Ohgita, Takashi
Tamagaki-Asahina, Hiroko
Nishitsuji, Kazuchika
Shimanouchi, Toshinori
Sato, Takeshi
Saito, Hiroyuki
Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title_full Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title_fullStr Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title_full_unstemmed Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title_short Amyloidogenic 60–71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects
title_sort amyloidogenic 60–71 deletion/valthr insertion mutation of apolipoprotein a-i generates a new aggregation-prone segment that promotes nucleation through entropic effects
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10613298/
https://www.ncbi.nlm.nih.gov/pubmed/37898709
http://dx.doi.org/10.1038/s41598-023-45803-y
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