Metabolome Analysis Revealed Increase in S-Methylcysteine and Phosphatidylisopropanolamine Synthesis upon L-Cysteine Deprivation in the Anaerobic Protozoan Parasite Entamoeba histolytica
Metabolome Analysis Revealed Increase in S-Methylcysteine and Phosphatidylisopropanolamine Synthesis upon L-Cysteine Deprivation in the Anaerobic Protozoan Parasite Entamoeba histolytica
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DOI：
10.1074/jbc.m110.167304
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发表时间：
2010-12-01
影响因子：
4.8
通讯作者：
Nozaki, Tomoyoshi
中科院分区：
文献类型：
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作者：
Husain, Afzal;Sato, Dan;Nozaki, Tomoyoshi
L-半胱氨酸普遍存在于所有生物体中，并参与多种功能，包括铁硫簇和谷胱甘肽的合成以及蛋白质结构，稳定性和催化的调节。在原生动物寄生虫溶组织内阿米巴（阿米巴病的病原体）中，L-半胱氨酸在增殖、粘附和防御氧化应激中起着重要作用;然而，这种氨基酸在其调节的途径中的重要性还不清楚。在本研究中，我们应用毛细管电泳飞行时间质谱法对E. histolytica，其被选择作为用于检查L-半胱氨酸的生物学作用的模型。L-半胱氨酸剥夺对糖酵解、氨基酸和磷脂代谢产生深远影响，L-半胱氨酸、L-胱氨酸和S-腺苷甲硫氨酸水平急剧下降，O-乙酰丝氨酸和S-甲基半胱氨酸急剧积累。我们进一步证明了S-甲基半胱氨酸是由甲烷硫醇和O-乙酰丝氨酸通过半胱氨酸合成酶合成的，该半胱氨酸合成酶以前被认为参与硫同化L-半胱氨酸的生物合成。此外，L-半胱氨酸消耗抑制糖酵解和能量产生，因为它减少乙酰辅酶A，乙醇和主要的核苷酸二磷酸和三磷酸，并导致糖酵解中间体的积累。有趣的是，L-半胱氨酸耗竭增加了异丙醇胺和磷脂酰异丙醇胺的合成，并证实它们的增加不是氧化应激的结果，而是对L-半胱氨酸耗竭的特异性反应。我们还确定了一个途径，其中异丙醇胺合成由丙酮醛通过氨基丙酮。到目前为止，这项研究代表了第一例L-半胱氨酸剥夺导致核心代谢途径（包括能量、氨基酸和磷脂代谢）发生剧烈变化的病例。
L-Cysteine is ubiquitous in all living organisms and is involved in a variety of functions, including the synthesis of iron-sulfur clusters and glutathione and the regulation of the structure, stability, and catalysis of proteins. In the protozoan parasite Entamoeba histolytica, the causative agent of amebiasis, L-cysteine plays an essential role in proliferation, adherence, and defense against oxidative stress; however, the essentiality of this amino acid in the pathways it regulates is not well understood. In the present study, we applied capillary electrophoresis time-of-flight mass spectrometry to quantitate charged metabolites modulated in response to L-cysteine deprivation in E. histolytica, which was selected as a model for examining the biological roles of L-cysteine. L-Cysteine deprivation had profound effects on glycolysis, amino acid, and phospholipid metabolism, with sharp decreases in the levels of L-cysteine, L-cystine, and S-adenosylmethionine and a dramatic accumulation of O-acetylserine and S-methylcysteine. We further demonstrated that S-methylcysteine is synthesized from methanethiol and O-acetylserine by cysteine synthase, which was previously considered to be involved in sulfur-assimilatory L-cysteine biosynthesis. In addition, L-cysteine depletion repressed glycolysis and energy generation, as it reduced acetylCoA, ethanol, and the major nucleotide di- and triphosphates, and led to the accumulation of glycolytic intermediates. Interestingly, L-cysteine depletion increased the synthesis of isopropanolamine and phosphatidylisopropanolamine, and it was confirmed that their increment was not a result of oxidative stress but was a specific response to L-cysteine depletion. We also identified a pathway in which isopropanolamine is synthesized from methylglyoxal via aminoacetone. To date, this study represents the first case where L-cysteine deprivation leads to drastic changes in core metabolic pathways, including energy, amino acid, and phospholipid metabolism.