Laboratory of Plant Molecular Biology, Faculty of Life Sciences and Biotechnology, South Asian University, Akbar Bhawan, Chanakyapuri, New Delhi, 110021, India.
Sci Rep. 2020 Jul 30;10(1):12835. doi: 10.1038/s41598-020-69742-0.
D-lactate dehydrogenase (D-LDH) converts D-lactate (the end product of glyoxalase system) to pyruvate and thereby completes the detoxification process of methylglyoxal. D-LDH detoxifies and diverts the stress induced toxic metabolites, MG and D-lactate, towards energy production and thus, protects the cell from their deteriorating effects. In this study, a D-LDH enzyme from rice (OsD-LDH2, encoded by Os07g08950.1) was characterized for its role in abiotic stress tolerance. For this, a combination of in silico, molecular, genetic and biochemical approaches was used. The kinetic analysis revealed OsD-LDH2 to be the most efficient D-LDH enzyme in comparison to D-LDHs from other plant species. Heterologous overexpression of OsD-LDH2 provides tolerance against multiple abiotic stresses in E. coli, yeast and plant system. The analysis of D-LDH mutant and OsD-LDH2 overexpressing transgenic plants uncovered the crucial role of D-LDH in mitigation of abiotic stresses. OsD-LDH2 overexpressing plants maintained lower level of ROS and other toxic metabolites along with better functioning of antioxidant system. This is the first report on correlation of D-LDH with multiple abiotic stress tolerance. Overall, OsD-LDH2 emerged as a promising candidate which can open a new direction for engineering stress tolerant crop varieties by maintaining their growth and yield in unfavorable conditions.
D-乳酸脱氢酶（D-LDH）将 D-乳酸（乙二醛酶系统的终产物）转化为丙酮酸，从而完成甲基乙二醛的解毒过程。D-LDH 解毒并转移应激诱导的有毒代谢物 MG 和 D-乳酸，以产生能量，从而保护细胞免受其恶化影响。在这项研究中，从水稻中鉴定出一种 D-LDH 酶（由 Os07g08950.1 编码的 OsD-LDH2），以研究其在非生物胁迫耐受性中的作用。为此，采用了计算机模拟、分子、遗传和生化方法相结合的方法。动力学分析表明，与其他植物物种的 D-LDH 相比，OsD-LDH2 是最有效的 D-LDH 酶。OsD-LDH2 的异源过表达为大肠杆菌、酵母和植物系统提供了对多种非生物胁迫的耐受性。D-LDH 突变体和 OsD-LDH2 过表达转基因植物的分析揭示了 D-LDH 在减轻非生物胁迫中的关键作用。OsD-LDH2 过表达的植物保持较低水平的 ROS 和其他有毒代谢物，同时具有更好的抗氧化系统功能。这是 D-LDH 与多种非生物胁迫耐受性相关的首次报道。总的来说，OsD-LDH2 是一种很有前途的候选蛋白，它可以通过在不利条件下维持其生长和产量，为工程耐胁迫作物品种开辟新的方向。
