Koechler Sandrine, Bertin Philippe N, Plewniak Frédéric, Baltenweck Raymonde, Casiot Corinne, Heipieper Hermann J, Bouchez Olivier, Arsène-Ploetze Florence, Hugueney Philippe, Halter David
Génétique Moléculaire, Génomique et Microbiologie, Département Microorganismes, Génomes, Environnement UMR7156 Université de Strasbourg/CNRS, 28 rue Goethe, 67083, Strasbourg Cedex, France.
Unité Mixte de Recherche Santé de la Vigne et Qualité du Vin, Equipe Métabolisme secondaire de la vigne INRA, 68021, Colmar, France.
Environ Microbiol. 2016 Apr;18(4):1289-300. doi: 10.1111/1462-2920.13227. Epub 2016 Feb 15.
Arsenic is a toxic metalloid known to generate an important oxidative stress in cells. In the present study, we focused our attention on an alga related to the genus Coccomyxa, exhibiting an extraordinary capacity to resist high concentrations of arsenite and arsenate. The integrated analysis of high-throughput transcriptomic data and non-targeted metabolomic approaches highlighted multiple levels of protection against arsenite. Indeed, Coccomyxa sp. Carn induced a set of transporters potentially preventing the accumulation of this metalloid in the cells and presented a distinct arsenic metabolism in comparison to another species more sensitive to that compound, i.e. Euglena gracilis, especially in regard to arsenic methylation. Interestingly, Coccomyxa sp. Carn was characterized by a remarkable accumulation of the strong antioxidant glutathione (GSH). Such observation could explain the apparent low oxidative stress in the intracellular compartment, as suggested by the transcriptomic analysis. In particular, the high amount of GSH in the cell could play an important role for the tolerance to arsenate, as suggested by its partial oxidation into oxidized glutathione in presence of this metalloid. Our results therefore reveal that this alga has acquired multiple and original defence mechanisms allowing the colonization of extreme ecosystems such as acid mine drainages.
砷是一种有毒类金属，已知会在细胞中产生重要的氧化应激。在本研究中，我们将注意力集中在一种与球囊藻属相关的藻类上，它表现出非凡的抵抗高浓度亚砷酸盐和砷酸盐的能力。高通量转录组数据和非靶向代谢组学方法的综合分析突出了针对亚砷酸盐的多层次保护。事实上，嗜砷球囊藻诱导了一组转运蛋白，可能阻止这种类金属在细胞中的积累，并且与另一种对该化合物更敏感的物种（即纤细裸藻）相比，呈现出独特的砷代谢，特别是在砷甲基化方面。有趣的是，嗜砷球囊藻的特征是强力抗氧化剂谷胱甘肽（GSH）的显著积累。如转录组分析所示，这种观察结果可以解释细胞内区室中明显较低的氧化应激。特别是，细胞中大量的谷胱甘肽可能对耐受砷酸盐起重要作用，正如在这种类金属存在下它部分氧化为氧化型谷胱甘肽所表明的那样。因此，我们的结果表明，这种藻类已经获得了多种独特的防御机制，使其能够在极端生态系统（如酸性矿山排水区）中定殖。
