Division of Biotechnology, Dalian Institute of Chemical Physics, CAS, 457 Zhongshan Road, Dalian, China.
Appl Microbiol Biotechnol. 2012 May;94(4):1095-105. doi: 10.1007/s00253-011-3820-3. Epub 2012 Jan 6.
Early biochemical studies have demonstrated that lipid accumulation by oleaginous yeasts is linked to the activity of the NAD(+)-dependent isocitrate dehydrogenase (Idh). However, molecular study of Idh of oleaginous microorganisms remains limited. Here, we present the cloning of a mitochondrial NAD(+)-specific Idh from Rhodosporidium toruloides (RtIdh), an excellent microbial lipid producer that uses carbohydrates as the carbon source. The evolutionary relationship analyses among RtIdhs and other yeast Idhs revealed that RtIdh had a closer relationship with the Idhs of Ustilago maydis and Schizophyllum commune. We expressed the RtIDH gene in the yeast Saccharomyces cerevisiae idhΔ mutant. Under the nitrogen-limited condition, the intracellular lipid content and extracellular citrate concentration of the culture of the S. cerevisiae idhΔ carrying the RtIDH gene increased as the carbon/nitrogen molar ratio of the media increased, while the wild-type S. cerevisiae strain showed no correlation. Our data provided valuable information for elucidating the molecular mechanism of microbial oleaginicity and for engineering microorganisms to produce metabolites of fatty acid pathway.
早期的生化研究表明，油脂酵母的脂类积累与 NAD(+)-依赖的异柠檬酸脱氢酶 (Idh) 的活性有关。然而，油脂微生物的 Idh 的分子研究仍然有限。在这里，我们从产油微生物 Rhodosporidium toruloides (RtIdh) 中克隆了一种线粒体 NAD(+)-特异性的 Idh，R. toruloides 是一种优秀的微生物油脂生产菌，它以碳水化合物作为碳源。RtIdh 与其他酵母 Idh 的进化关系分析表明，RtIdh 与 Ustilago maydis 和 Schizophyllum commune 的 Idh 关系更为密切。我们在酵母 Saccharomyces cerevisiae idhΔ 突变体中表达了 RtIDH 基因。在氮限制条件下，携带 RtIDH 基因的 S. cerevisiae idhΔ 培养物的细胞内脂质含量和细胞外柠檬酸浓度随着培养基的碳/氮摩尔比的增加而增加，而野生型 S. cerevisiae 菌株则没有相关性。我们的数据为阐明微生物油脂形成的分子机制以及为工程微生物生产脂肪酸途径的代谢产物提供了有价值的信息。
