Department of Microbiology and Molecular Genetics, The Institute For Medical Reseach Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, 9112102 Jerusalem, Israel.
Campus for Research Excellence And Technological Enterprise (CREATE)-National University Of Singapore (NUS)-Hebrew University Of Jerusalem (HUJ), Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 138602 Singapore, Singapore.
Proc Natl Acad Sci U S A. 2021 Jun 8;118(23). doi: 10.1073/pnas.2026595118.
Class-II fumarases (fumarate hydratase, FH) are dual-targeted enzymes occurring in the mitochondria and cytosol of all eukaryotes. They are essential components in the DNA damage response (DDR) and, more specifically, protect cells from DNA double-strand breaks. Similarly, the gram-positive bacterium class-II fumarase, in addition to its role in the tricarboxylic acid cycle, participates in the DDR. harbors three fumarase genes: class-I and and class-II Notably, class-I fumarases show no sequence similarity to class-II fumarases and are of different evolutionary origin. Strikingly, here we show that fumarase functions are distributed between class-I fumarases, which participate in the DDR, and the class-II fumarase, which participates in respiration. In , we discover that the signaling molecule, alpha-ketoglutarate (α-KG), has a function, complementing DNA damage sensitivity of -null mutants. Excitingly, we identify the α-KG-dependent DNA repair enzyme AlkB as the target of this interplay of metabolite signaling. In addition to α-KG, fumarate (fumaric acid) is shown to affect DNA damage repair on two different levels, first by directly inhibiting the DNA damage repair enzyme AlkB demethylase activity, both in vitro and in vivo (countering α-KG). The second is a more global effect on transcription, because -null mutants exhibit a decrease in transcription of key DNA damage repair genes. Together, these results show evolutionary adaptable metabolic signaling of the DDR, in which fumarases and different metabolites are recruited regardless of the evolutionary enzyme class performing the function.
II 型富马酶（延胡索酸水合酶，FH）是一种存在于所有真核生物的线粒体和细胞质中的双靶标酶。它们是 DNA 损伤反应（DDR）的重要组成部分，更具体地说，它们可以保护细胞免受 DNA 双链断裂的影响。同样，革兰氏阳性细菌 II 型富马酶除了在三羧酸循环中的作用外，还参与 DDR。 含有三个富马酶基因：I 型 和 以及 II 型 值得注意的是，I 型富马酶与 II 型富马酶没有序列相似性，并且具有不同的进化起源。引人注目的是，我们在这里表明， 富马酶的功能分布在参与 DDR 的 I 型富马酶和参与呼吸作用的 II 型富马酶之间。在 中，我们发现信号分子α-酮戊二酸（α-KG）具有功能，可补充 -null 突变体的 DNA 损伤敏感性。令人兴奋的是，我们确定了依赖 α-KG 的 DNA 修复酶 AlkB 作为这种代谢物信号相互作用的靶标。除了 α-KG 外，富马酸盐（富马酸）还显示出在两个不同水平上影响 DNA 损伤修复的作用，首先通过直接抑制 DNA 损伤修复酶 AlkB 脱甲基酶活性，无论是在体外还是体内（与 α-KG 对抗）。第二个是对转录的更全局影响，因为 -null 突变体表现出关键 DNA 损伤修复基因转录的减少。总之，这些结果表明 DDR 的进化适应性代谢信号，其中富马酶和不同的代谢物被招募，无论执行功能的进化酶类如何。
