Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.

Tardigrades are able to tolerate almost complete dehydration by entering a reversible ametabolic state called anhydrobiosis and resume their animation upon rehydration. Dehydrated tardigrades are exceptionally stable and withstand various physical extremes. Although trehalose and late embryogenesis...

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Main Authors: Akihiro Tanaka, Tomomi Nakano, Kento Watanabe, Kazutoshi Masuda, Gen Honda, Shuichi Kamata, Reitaro Yasui, Hiroko Kozuka-Hata, Chiho Watanabe, Takumi Chinen, Daiju Kitagawa, Satoshi Sawai, Masaaki Oyama, Miho Yanagisawa, Takekazu Kunieda
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2022-09-01
Series:PLoS Biology
Online Access:https://doi.org/10.1371/journal.pbio.3001780
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author Akihiro Tanaka
Tomomi Nakano
Kento Watanabe
Kazutoshi Masuda
Gen Honda
Shuichi Kamata
Reitaro Yasui
Hiroko Kozuka-Hata
Chiho Watanabe
Takumi Chinen
Daiju Kitagawa
Satoshi Sawai
Masaaki Oyama
Miho Yanagisawa
Takekazu Kunieda
author_facet Akihiro Tanaka
Tomomi Nakano
Kento Watanabe
Kazutoshi Masuda
Gen Honda
Shuichi Kamata
Reitaro Yasui
Hiroko Kozuka-Hata
Chiho Watanabe
Takumi Chinen
Daiju Kitagawa
Satoshi Sawai
Masaaki Oyama
Miho Yanagisawa
Takekazu Kunieda
author_sort Akihiro Tanaka
collection DOAJ
description Tardigrades are able to tolerate almost complete dehydration by entering a reversible ametabolic state called anhydrobiosis and resume their animation upon rehydration. Dehydrated tardigrades are exceptionally stable and withstand various physical extremes. Although trehalose and late embryogenesis abundant (LEA) proteins have been extensively studied as potent protectants against dehydration in other anhydrobiotic organisms, tardigrades produce high amounts of tardigrade-unique protective proteins. Cytoplasmic-abundant heat-soluble (CAHS) proteins are uniquely invented in the lineage of eutardigrades, a major class of the phylum Tardigrada and are essential for their anhydrobiotic survival. However, the precise mechanisms of their action in this protective role are not fully understood. In the present study, we first postulated the presence of tolerance proteins that form protective condensates via phase separation in a stress-dependent manner and searched for tardigrade proteins that reversibly form condensates upon dehydration-like stress. Through a comprehensive search using a desolvating agent, trifluoroethanol (TFE), we identified 336 proteins, collectively dubbed "TFE-Dependent ReversiblY condensing Proteins (T-DRYPs)." Unexpectedly, we rediscovered CAHS proteins as highly enriched in T-DRYPs, 3 of which were major components of T-DRYPs. We revealed that these CAHS proteins reversibly polymerize into many cytoskeleton-like filaments depending on hyperosmotic stress in cultured cells and undergo reversible gel-transition in vitro. Furthermore, CAHS proteins increased cell stiffness in a hyperosmotic stress-dependent manner and counteract the cell shrinkage caused by osmotic pressure, and even improved the survival against hyperosmotic stress. The conserved putative helical C-terminal region is necessary and sufficient for filament formation by CAHS proteins, and mutations disrupting the secondary structure of this region impaired both the filament formation and the gel transition. On the basis of these results, we propose that CAHS proteins are novel cytoskeleton-like proteins that form filamentous networks and undergo gel-transition in a stress-dependent manner to provide on-demand physical stabilization of cell integrity against deformative forces during dehydration and could contribute to the exceptional physical stability in a dehydrated state.
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spelling doaj.art-6d429528361a4d5db6190332612ca6af2022-12-22T03:28:23ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852022-09-01209e300178010.1371/journal.pbio.3001780Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.Akihiro TanakaTomomi NakanoKento WatanabeKazutoshi MasudaGen HondaShuichi KamataReitaro YasuiHiroko Kozuka-HataChiho WatanabeTakumi ChinenDaiju KitagawaSatoshi SawaiMasaaki OyamaMiho YanagisawaTakekazu KuniedaTardigrades are able to tolerate almost complete dehydration by entering a reversible ametabolic state called anhydrobiosis and resume their animation upon rehydration. Dehydrated tardigrades are exceptionally stable and withstand various physical extremes. Although trehalose and late embryogenesis abundant (LEA) proteins have been extensively studied as potent protectants against dehydration in other anhydrobiotic organisms, tardigrades produce high amounts of tardigrade-unique protective proteins. Cytoplasmic-abundant heat-soluble (CAHS) proteins are uniquely invented in the lineage of eutardigrades, a major class of the phylum Tardigrada and are essential for their anhydrobiotic survival. However, the precise mechanisms of their action in this protective role are not fully understood. In the present study, we first postulated the presence of tolerance proteins that form protective condensates via phase separation in a stress-dependent manner and searched for tardigrade proteins that reversibly form condensates upon dehydration-like stress. Through a comprehensive search using a desolvating agent, trifluoroethanol (TFE), we identified 336 proteins, collectively dubbed "TFE-Dependent ReversiblY condensing Proteins (T-DRYPs)." Unexpectedly, we rediscovered CAHS proteins as highly enriched in T-DRYPs, 3 of which were major components of T-DRYPs. We revealed that these CAHS proteins reversibly polymerize into many cytoskeleton-like filaments depending on hyperosmotic stress in cultured cells and undergo reversible gel-transition in vitro. Furthermore, CAHS proteins increased cell stiffness in a hyperosmotic stress-dependent manner and counteract the cell shrinkage caused by osmotic pressure, and even improved the survival against hyperosmotic stress. The conserved putative helical C-terminal region is necessary and sufficient for filament formation by CAHS proteins, and mutations disrupting the secondary structure of this region impaired both the filament formation and the gel transition. On the basis of these results, we propose that CAHS proteins are novel cytoskeleton-like proteins that form filamentous networks and undergo gel-transition in a stress-dependent manner to provide on-demand physical stabilization of cell integrity against deformative forces during dehydration and could contribute to the exceptional physical stability in a dehydrated state.https://doi.org/10.1371/journal.pbio.3001780
spellingShingle Akihiro Tanaka
Tomomi Nakano
Kento Watanabe
Kazutoshi Masuda
Gen Honda
Shuichi Kamata
Reitaro Yasui
Hiroko Kozuka-Hata
Chiho Watanabe
Takumi Chinen
Daiju Kitagawa
Satoshi Sawai
Masaaki Oyama
Miho Yanagisawa
Takekazu Kunieda
Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
PLoS Biology
title Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
title_full Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
title_fullStr Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
title_full_unstemmed Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
title_short Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.
title_sort stress dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel
url https://doi.org/10.1371/journal.pbio.3001780
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