PDF(Pubmed)
Abstract：
Mitochondria are central to cellular metabolism; hence, their dysfunction contributes to a wide array of human diseases including cancer, cardiopathy, neurodegeneration, and heritable pathologies such as Barth syndrome. Cardiolipin, the signature phospholipid of the mitochondrion promotes proper cristae morphology, bioenergetic functions, and directly affects metabolic reactions carried out in mitochondrial membranes. To match tissue-specific metabolic demands, cardiolipin typically undergoes an acyl tail remodeling process with the final step carried out by the phospholipid-lysophospholipid transacylase tafazzin. Mutations in the tafazzin gene are the primary cause of Barth syndrome. Here, we investigated how defects in cardiolipin biosynthesis and remodeling impact metabolic flux through the tricarboxylic acid cycle and associated pathways in yeast. Nuclear magnetic resonance was used to monitor in real-time the metabolic fate of 13C3-pyruvate in isolated mitochondria from three isogenic yeast strains. We compared mitochondria from a wild-type strain to mitochondria from a Δtaz1 strain that lacks tafazzin and contains lower amounts of unremodeled cardiolipin, and mitochondria from a Δcrd1 strain that lacks cardiolipin synthase and cannot synthesize cardiolipin. We found that the 13C-label from the pyruvate substrate was distributed through about twelve metabolites. Several of the identified metabolites were specific to yeast pathways, including branched chain amino acids and fusel alcohol synthesis. Most metabolites showed similar kinetics amongst the different strains but mevalonate and α-ketoglutarate, as well as the NAD+/NADH couple measured in separate nuclear magnetic resonance experiments, showed pronounced differences. Taken together, the results show that cardiolipin remodeling influences pyruvate metabolism, tricarboxylic acid cycle flux, and the levels of mitochondrial nucleotides.
摘要：
线粒体是细胞代谢的核心；因此，它们的功能障碍导致了一系列广泛的人类疾病，包括癌症，心脏病,神经变性,和遗传性病变，如巴特综合征。心磷脂,线粒体的标志性磷脂促进适当的cr形态，生物能量功能，并直接影响线粒体膜中进行的代谢反应。为了匹配组织特异性代谢需求，心磷脂通常经历酰基尾重塑过程，最后一步由磷脂-溶血磷脂转酰酶taafazzin进行。Tafazzin基因突变是Barth综合征的主要原因。这里,我们研究了酵母中心磷脂生物合成和重塑缺陷如何通过三羧酸循环和相关途径影响代谢通量。核磁共振用于实时监测来自三个等基因酵母菌株的分离线粒体中13C3-丙酮酸的代谢命运。我们将野生型菌株的线粒体与缺乏tafazzin且含有较低量的未重塑心磷脂的Δtaz1菌株的线粒体进行了比较，和来自缺乏心磷脂合酶且无法合成心磷脂的Δcrd1菌株的线粒体。我们发现来自丙酮酸底物的13C标记通过约12种代谢物分布。几种鉴定的代谢物对酵母途径具有特异性，包括支链氨基酸和杂醇合成。大多数代谢物在不同菌株中表现出相似的动力学，但甲羟戊酸和α-酮戊二酸，以及在单独的核磁共振实验中测量的NAD+/NADH对，显示出明显的差异。一起来看,结果表明，心磷脂重塑影响丙酮酸代谢，三羧酸循环通量，和线粒体核苷酸的水平。
