Biochemical and structural characterization of an endoplasmic reticulum-localized late embryogenesis abundant (LEA) protein from the liverwort Marchantia polymorpha |
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Authors: | Rie Hatanaka Takao Furuki Tempei Shimizu Daisuke Takezawa Takahiro Kikawada Minoru Sakurai Yasutake Sugawara |
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Institution: | 1. National Institute of Agrobiological Sciences, 1-2 Ohwashi, Tsukuba 305-8634, Japan;2. Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B-62, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan;3. Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan |
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Abstract: | Late embryogenesis abundant (LEA) proteins, which accumulate to high levels in seeds during late maturation, are associated with desiccation tolerance. A member of the LEA protein family was found in cultured cells of the liverwort Marchantia polymorpha; preculture treatment of these cells with 0.5 M sucrose medium led to their acquisition of desiccation tolerance. We characterized this preculture-induced LEA protein, designated as MpLEA1. MpLEA1 is predominantly hydrophilic with a few hydrophobic residues that may represent its putative signal peptide. The protein also contains a putative endoplasmic reticulum (ER) retention sequence, HEEL, at the C-terminus. Microscopic observations indicated that GFP-fused MpLEA1 was mainly localized in the ER. The recombinant protein MpLEA1 is intrinsically disordered in solution. On drying, MpLEA1 shifted predominantly toward α-helices from random coils. Such changes in conformation are a typical feature of the group 3 LEA proteins. Recombinant MpLEA1 prevented the aggregation of α-casein during desiccation–rehydration events, suggesting that MpLEA1 exerts anti-aggregation activity against desiccation-sensitive proteins by functioning as a “molecular shield”. Moreover, the anti-aggregation activity of MpLEA1 was ten times greater than that of BSA or insect LEA proteins, which are known to prevent aggregation on drying. Here, we show that an ER-localized LEA protein, MpLEA1, possesses biochemical and structural features specific to group 3 LEA proteins. |
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Keywords: | CD circular dichroism CHO Chinese hamster ovary ER endoplasmic reticulum FT-IR Fourier transform-infrared IPTG isopropyl β-d-1-thiogalactopyranoside LEA late embryogenesis abundant |
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