Ustilago maydis produces itaconic acid via the unusual intermediate trans-aconitate.
Ustilago maydis produces itaconic acid via the unusual intermediate trans-aconitate.
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DOI：
10.1111/1751-7915.12329
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发表时间：
2016-01
影响因子：
5.7
通讯作者：
Bölker M
中科院分区：
文献类型：
--
作者：
Geiser E;Przybilla SK;Friedrich A;Buckel W;Wierckx N;Blank LM;Bölker M
衣康酸是一种重要的生物质衍生化学构件，但最近也被确定为哺乳动物产生的代谢物，具有抗菌活性。子囊菌土曲霉和人巨噬细胞中衣康酸的生物合成途径已被阐明。在这两种生物体中，衣康酸是通过三羧酸（TCA）循环中间体顺乌头酸脱羧产生的。在这里，我们表明，担子菌真菌玉米 U stilago maydis 使用替代途径并通过反式乌头酸（热力学上有利的顺式乌头酸异构体）产生衣康酸。我们已经鉴定出一个基因簇，其中包含参与衣康酸形成的所有基因。反式乌头酸是由顺式乌头酸通过胞质乌头酸-Δ-异构酶 (Adi1) 生成的，该酶属于参与细菌丙酸降解的 PrpF 蛋白家族。反式乌头酸脱羧由一种新型酶反式乌头酸脱羧酶 (Tad1) 催化。 Tad1 与细菌 3-羧基-顺,顺-粘康酸内酯化酶 (CMLE) 显示出显着的序列相似性。这表明 U . maydis 开发了一种使用有毒中间体反乌头酸生产衣康酸的替代生物合成途径。途径特异性转录因子 (Ria1) 或线粒体三羧酸转运蛋白 (Mtt1) 的过度表达导致衣康酸产量增加两倍。因此，我们的研究结果为这种有价值的生物质衍生化学品的生物技术生产提供了新策略。
Itaconic acid is an important biomass‐derived chemical building block but has also recently been identified as a metabolite produced in mammals, which has antimicrobial activity. The biosynthetic pathway of itaconic acid has been elucidated in the ascomycetous fungus A spergillus terreus and in human macrophages. In both organisms itaconic acid is generated by decarboxylation of the tricarboxylic acid (TCA) cycle intermediate cis‐aconitate. Here, we show that the basidiomycetous fungus U stilago maydis uses an alternative pathway and produces itaconic acid via trans‐aconitate, the thermodynamically favoured isomer of cis‐aconitate. We have identified a gene cluster that contains all genes involved in itaconic acid formation. Trans‐aconitate is generated from cis‐aconitate by a cytosolic aconitate‐Δ‐isomerase (Adi1) that belongs to the PrpF family of proteins involved in bacterial propionate degradation. Decarboxylation of trans‐aconitate is catalyzed by a novel enzyme, trans‐aconitate decarboxylase (Tad1). Tad1 displays significant sequence similarity with bacterial 3‐carboxy‐cis,cis‐muconate lactonizing enzymes (CMLE). This suggests that U . maydis has evolved an alternative biosynthetic pathway for itaconate production using the toxic intermediate trans‐aconitate. Overexpression of a pathway‐specific transcription factor (Ria1) or a mitochondrial tricarboxylic acid transporter (Mtt1) resulted in a twofold increase in itaconate yield. Therefore, our findings offer new strategies for biotechnological production of this valuable biomass‐derived chemical.