Molecular chaperones play an important role during the response to different stresses. Since plants are sessile organisms, they need to be able to adapt quickly to different conditions. To do so, plants possess a complex chaperone machinery, composed of HSP70, HSP90, J proteins and other factors. In this study we characterized DJC31 (also known as TPR16) and DJC62 (also known as TPR15) of Arabidopsis thaliana, two J proteins that additionally carry clamp-type tetratricopeptide repeat domains. Using cell fractionation and split GFP, we could show that both proteins are attached to the cytosolic side of the endoplasmic reticulum membrane. Moreover, an interaction with cytosolic HSP70.1 and HSP90.2 could be shown using bimolecular fluorescence complementation. Knockout of both DJC31 and DJC62 caused severe defects in growth and development, which affected almost all organs. Furthermore, it could be shown that the double mutant is more sensitive to osmotic stress and treatment with abscisic acid, but surprisingly exhibited enhanced tolerance to drought. Taken together, these findings indicate that DJC31 and DJC62 might act as important regulators of chaperone-dependent signaling pathways involved in plant development and stress responses.

中文翻译：

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含有 TPR 和 J 结构域的蛋白质 DJC31 和 DJC62 参与拟南芥的非生物应激反应。

分子伴侣在应对不同压力的过程中发挥着重要作用。由于植物是固着的生物，它们需要能够快速适应不同的条件。为此，植物拥有复杂的伴侣机制，由 HSP70、HSP90、J 蛋白和其他因子组成。在这项研究中，我们表征了拟南芥的 DJC31（也称为 TPR16）和 DJC62（也称为 TPR15），这两种 J 蛋白还携带钳型四肽重复结构域。使用细胞分级分离和分裂 GFP，我们可以证明这两种蛋白质都附着在内质网膜的胞质侧。此外，可以使用双分子荧光互补显示与胞质 HSP70.1 和 HSP90.2 的相互作用。敲除 DJC31 和 DJC62 导致生长发育严重缺陷，这几乎影响了所有器官。此外，可以显示双突变体对渗透胁迫和脱落酸处理更敏感，但令人惊讶地表现出对干旱的增强耐受性。总之，这些发现表明 DJC31 和 DJC62 可能是参与植物发育和应激反应的伴侣依赖信号通路的重要调节剂。