Shimizu Motoyuki
a Faculty of Agriculture, Department of Applied Biological Chemistry , Meijo University , Nagoya , Japan.
Biosci Biotechnol Biochem. 2018 Feb;82(2):216-224. doi: 10.1080/09168451.2017.1422972. Epub 2018 Jan 12.
Filamentous fungi are used to produce fermented foods, organic acids, beneficial secondary metabolites and various enzymes. During such processes, these fungi balance cellular NAD:NADH ratios to adapt to environmental redox stimuli. Cellular NAD(H) status in fungal cells is a trigger of changes in metabolic pathways including those of glycolysis, fermentation, and the production of organic acids, amino acids and secondary metabolites. Under hypoxic conditions, high NADH:NAD ratios lead to the inactivation of various dehydrogenases, and the metabolic flow involving NAD is down-regulated compared with normoxic conditions. This review provides an overview of the metabolic mechanisms of filamentous fungi under hypoxic conditions that alter the cellular NADH:NAD balance. We also discuss the relationship between the intracellular redox balance (NAD/NADH ratio) and the production of beneficial secondary metabolites that arise from repressing the HDAC activity of sirtuin A via Nudix hydrolase A (NdxA)-dependent NAD degradation.
丝状真菌被用于生产发酵食品、有机酸、有益的次生代谢产物和各种酶。在这些过程中，这些真菌平衡细胞内NAD:NADH比例以适应环境氧化还原刺激。真菌细胞中的细胞NAD(H)状态是包括糖酵解、发酵以及有机酸、氨基酸和次生代谢产物生产等代谢途径变化的触发因素。在缺氧条件下，高NADH:NAD比例会导致各种脱氢酶失活，与常氧条件相比，涉及NAD的代谢流下调。本综述概述了丝状真菌在缺氧条件下改变细胞NADH:NAD平衡的代谢机制。我们还讨论了细胞内氧化还原平衡（NAD/NADH比例）与通过依赖Nudix水解酶A（NdxA）的NAD降解抑制沉默调节蛋白A的组蛋白去乙酰化酶活性而产生有益次生代谢产物之间的关系。
