Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany.
FEMS Microbiol Lett. 2013 Feb;339(1):17-22. doi: 10.1111/1574-6968.12041. Epub 2012 Nov 28.
The Gram-positive soil bacterium Bacillus subtilis uses glucose and malate as the preferred carbon sources. In the presence of either glucose or malate, the expression of genes and operons for the utilization of secondary carbon sources is subject to carbon catabolite repression. While glucose is a preferred substrate in many organisms from bacteria to man, the factors that contribute to the preference for malate have so far remained elusive. In this work, we have studied the contribution of the different malate-metabolizing enzymes in B. subtilis, and we have elucidated their distinct functions. The malate dehydrogenase and the phosphoenolpyruvate carboxykinase are both essential for malate utilization; they introduce malate into gluconeogenesis. The NADPH-generating malic enzyme YtsJ is important to establish the cellular pools of NADPH for anabolic reactions. Finally, the NADH-generating malic enzymes MaeA, MalS, and MleA are involved in keeping the ATP levels high. Together, this unique array of distinct activities makes malate a preferred carbon source for B. subtilis.
革兰氏阳性土壤细菌枯草芽孢杆菌将葡萄糖和苹果酸用作首选碳源。在存在葡萄糖或苹果酸的情况下，利用次要碳源的基因和操纵子的表达受到碳分解代谢物阻遏的控制。虽然葡萄糖是许多从细菌到人等生物体的首选底物，但迄今为止，导致对苹果酸偏好的因素仍然难以捉摸。在这项工作中，我们研究了枯草芽孢杆菌中不同的苹果酸代谢酶的贡献，并阐明了它们的不同功能。苹果酸脱氢酶和磷酸烯醇丙酮酸羧激酶对于苹果酸的利用都是必需的；它们将苹果酸引入糖异生途径。产生 NADPH 的苹果酸酶 YtsJ 对于建立用于合成代谢反应的细胞 NADPH 池很重要。最后，产生 NADH 的苹果酸酶 MaeA、MalS 和 MleA 参与维持高水平的 ATP。总之，这种独特的一系列不同的活性使苹果酸成为枯草芽孢杆菌的首选碳源。
