Lehmann Julian, Jørgensen Morten E, Fratz Stefanie, Müller Heike M, Kusch Jana, Scherzer Sönke, Navarro-Retamal Carlos, Mayer Dominik, Böhm Jennifer, Konrad Kai R, Terpitz Ulrich, Dreyer Ingo, Mueller Thomas D, Sauer Markus, Hedrich Rainer, Geiger Dietmar, Maierhofer Tobias
Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Institute, Würzburg 97082, Germany; Department of Biotechnology and Biophysics, University of Würzburg, Biocenter -Am Hubland, Würzburg 97074, Germany.
Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Institute, Würzburg 97082, Germany.
Curr Biol. 2021 Aug 23;31(16):3575-3585.e9. doi: 10.1016/j.cub.2021.06.018. Epub 2021 Jul 6.
Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.
植物作为固着生物，获得了感知和响应生物及非生物胁迫的能力，以在其环境的剧烈变化中生存。气候变化带来了极端干旱期，也有洪水泛滥的情况。后一种胁迫条件会导致厌氧引发的胞质酸中毒，并损害植物功能。此前，植物细胞感知酸度并通过膜去极化传递该信号的分子机制尚不清楚。在这里，我们表明拟南芥（Arabidopsis thaliana）根中酸中毒诱导的阴离子外流依赖于S型阴离子通道AtSLAH3。SLAH3在非洲爪蟾卵母细胞中的异源表达表明，该阴离子通道直接被胞质pH值的微小生理性下降激活。酸中毒触发的SLAH3激活由组氨酸330和454的质子化介导。超分辨率显微镜分析表明，细胞质子浓度的增加将SLAH3从电沉默的通道二聚体转变为其活性单体形式。我们的结果表明，酸化时，质子直接将SLAH3转变为开放构象，绕过了激酶依赖性激活。此外，在水淹条件下，拟南芥野生型（WT）植株的胁迫响应明显高于SLAH3功能丧失突变体。我们关于SLAH3 pH传感器功能的遗传学证据可能会指导具有更强胁迫耐受性的作物品种的培育。
