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The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals.

ABSTRACT: Tardigrades, also known as water bears, are animals that can survive extreme conditions. The tardigrade Ramazzottius varieornatus contains a unique nuclear protein termed Dsup, for damage suppressor, which can increase the resistance of human cells to DNA damage under conditions, such as ionizing radiation or hydrogen peroxide treatment, that generate hydroxyl radicals. Here we find that R. varieornatus Dsup is a nucleosome-binding protein that protects chromatin from hydroxyl radicals. Moreover, a Dsup ortholog from the tardigrade Hypsibius exemplaris similarly binds to nucleosomes and protects DNA from hydroxyl radicals. Strikingly, a conserved region in Dsup proteins exhibits sequence similarity to the nucleosome-binding domain of vertebrate HMGN proteins and is functionally important for nucleosome binding and hydroxyl radical protection. These findings suggest that Dsup promotes the survival of tardigrades under diverse conditions by a direct mechanism that involves binding to nucleosomes and protecting chromosomal DNA from hydroxyl radicals.

SUBMITTER: Chavez C

PROVIDER: S-EPMC6773438 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals.

Chavez Carolina C Cruz-Becerra Grisel G Fei Jia J Kassavetis George A GA Kadonaga James T JT

eLife 20191001

Tardigrades, also known as water bears, are animals that can survive extreme conditions. The tardigrade <i>Ramazzottius varieornatus</i> contains a unique nuclear protein termed Dsup, for damage suppressor, which can increase the resistance of human cells to DNA damage under conditions, such as ionizing radiation or hydrogen peroxide treatment, that generate hydroxyl radicals. Here we find that <i>R. varieornatus</i> Dsup is a nucleosome-binding protein that protects chromatin from hydroxyl radi ...[more]

PMID: 31571581

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Project description:BackgroundIn the study, Folium Sennae (FS) was firstly extracted by various solvents to obtain five FS extracts. Then, five FS extracts were evaluated for the protective effects against •OH-induced DNA damage, antioxidant abilities in vitro, and chemical contents using various methods. On this basis, the correlation graphs between the pharmacological effects and chemical contents were plotted to obtain the correlation coefficients (R values). Finally, in order to obtain biological evidence, ethyl acetate extract of FS (EAFS) was investigated for the protective effect against •OH-induced MSCs (mesenchymal stem cells) damage using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl) assay.ResultsThe pharmacological assays indicated that five FS extracts could effectively protect against •OH-induced DNA damage. The correlation analysis suggested that the average R values of total phenolics, total anthraquinones, aloe-emodin, rhein, and emodin were respectively 0.843, 0.833, 0.753, 0.820, and 0.784, while those of total sugars and total saponins were respectively 0.103 and 0.0068. The mechanistic analysis revealed that five FS extracts could also scavenge •OH, •O2-, DPPH• & ABTS•+ radicals, and reduce Cu2+ to Cu+. MTT assay revealed that the viability of MSCs which were treated with •OH radicals has been effectively protected by EAFS (3 and 30 μg/mL).ConclusionOn this basis, it can be concluded that: (i) Folium Sennae exhibits a protective effect against •OH-induced damages to DNA and MSCs; (ii ) The effects may be attributed to phytophenols (especially aloe-emodin, rhein, and emodin), not sugars or saponins; (iii) They exert the protective action via hydrogen atom transfer (HAT) and/or sequential electron proton transfer (SEPT) mechanisms which make phenolic -OH moiety be oxidized to stable semi-quinone form; (iv) The stability of semi-quinone form can ultimately be responsible for the protective or antioxidant effect of phytophenols.

Dataset Information

The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals.

Publications

The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals.

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