Objectives

The transport of citrate from the mitochondria to the cytoplasm is essential during lipid accumulation. This study aimed to explore the role of mitochondrial citrate-oxoglutarate carrier in lipid accumulation in the oleaginous fungus Mortierella alpina.

Results

Homologous MaYHM (the gene encoding the mitochondrial citrate-oxoglutarate carrier) was overexpressed in M. alpina. The fatty acid content of MaYHM-overexpressing recombinant strains was increased by up to 30% compared with the control. Moreover, the intracellular α-ketoglutarate level in recombinant strains was increased by 2.2 fold, together with a 23–35% decrease in NAD⁺-isocitrate dehydrogenase activity compared with the control. The overexpression of MaYHM altered the metabolic flux in the glutamate dehydrogenase shunt and 4-aminobutyric acid shunt during metabolic reprogramming, supplying more carbon to synthesize fatty acids.

Conclusions

Overexpression of MaYHM resulted in more efflux of citrate from mitochondria to the cytoplasm and enhanced lipid accumulation. These findings provide new perspectives for the improvement of industrial lipid production in M. alpina.

中文翻译：

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线粒体柠檬酸-氧戊二酸载体在产油真菌高山被孢霉脂质积累中的作用

目标

在脂质积累过程中，柠檬酸盐从线粒体到细胞质的运输是必不可少的。本研究旨在探讨线粒体柠檬酸-氧戊二酸载体在产油真菌高山被孢霉脂质积累中的作用。

结果

同源MaYHM（编码线粒体柠檬酸酮戊二酸载体的基因）在过表达高山被孢霉。与对照相比，MaYHM过表达重组菌株的脂肪酸含量增加了 30%。此外，与对照相比，重组菌株的细胞内 α-酮戊二酸水平增加了 2.2 倍，同时 NAD ^{+ -}异柠檬酸脱氢酶活性降低了 23-35% 。MaYHM的过表达改变了代谢重编程期间谷氨酸脱氢酶分流和 4-氨基丁酸分流中的代谢通量，提供更多的碳来合成脂肪酸。

结论

MaYHM 的过表达导致更多的柠檬酸盐从线粒体流出到细胞质并增加脂质积累。这些发现为改善高山木霉的工业脂质生产提供了新的视角。