Diamine auxotrophy may be a universal feature of Trypanosoma cruzi epimastigotes
Diamine auxotrophy may be a universal feature of Trypanosoma cruzi epimastigotes
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DOI：
10.1016/s0166-6851(96)02788-0
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发表时间：
1997-01-01
影响因子：
1.5
通讯作者：
Fairlamb, AH
中科院分区：
文献类型：
--
作者：
Ariyanayagam, MR;Fairlamb, AH
多胺在许多细胞的正常生长和分化中起着重要和核心的作用。在锥虫中，亚精胺也是生物合成独特的谷胱甘肽-亚精胺偶联物--台盼硫酮的重要前体。我们先前的研究表明，克氏锥虫(Silvio株)的表鞭毛期不能从它们的氨基酸前体显著地从头合成腐胺或身体碱[Hunter，Le Quesne和Fairlamb(1994)毛皮]。J.生物化学。226、1019-1027]。在本研究中，我们发现在含有微量腐胺(0.22微米)和亚精胺(0.63微米)的培养基中，Y品系上鞭毛生长到对数末期时，含有低水平的以游离谷胱甘肽为主要低分子硫醇的多胺(占总谷胱甘肽的97%)。进入新鲜培养基后，色氨酸和谷胱甘肽亚精胺的含量在对数中期增加到总谷胱甘肽的46%，但在对数末期恢复到不到3%。相反，当接种外源腐胺时，谷胱甘肽-亚精胺结合物在早期对数阶段达到总谷胱甘肽的80%，并在整个生长过程中保持较高水平。在多胺饥饿期间(对数后期)补充外源腐胺或亚精胺会导致结合水平的增加(占总谷胱甘肽的74%)，并与总腐胺和亚精胺的大幅增加有关。同样，补充外源性身体碱和氨丙基身体碱会导致类似的台盼硫酮类似物和总身体碱和氨丙基身体碱的增加。相比之下，鸟氨酸、精氨酸、赖氨酸、胍丁胺和其他氨基酸前体对多胺或结合物水平没有影响。未检测到明显的鸟氨酸或精氨酸脱羧酶活性(<；0.8pmolmin(-1)[mg蛋白](-1))。对于代表所有主要酵母菌类别的表鞭毛体也得到了类似的结果，提供了二胺营养缺陷症可能是生命周期这一阶段的普遍特征的证据。版权所有(C)1997 Elsevier Science B.V.
Polyamines play an important and central role in normal cell growth and differentiation in many cells. In trypanosomatids, spermidine is also an essential precursor in the biosynthesis of the unique glutathione-spermidine conjugate, trypanothione. Our previous study has shown that the epimastigote stage of Trypanosoma cruzi (Silvio strain) is incapable of significant de novo synthesis of putrescine or cadaverine from their amino acid precursors [Hunter, Le Quesne and Fairlamb (1994) fur. J. Biochem. 226, 1019-1027]. In this study we show that when grown to late log phase in medium containing trace amounts of putrescine (0.22 mu M) and spermidine (0.63 mu M); Y-strain epimastigotes contain low levels of polyamines with free glutathione as their principal low molecular mass thiol (>97% of total glutathione). Following passage into fresh medium, trypanothione and glutathionylspermidine content increases to 46% of total glutathione by mid log phase but returns to less than 3% by late log phase. In contrast, when supplemented at inoculation with exogenous putrescine, glutathione-spermidine conjugates reach 80% of total glutathione by early log phase and remain elevated throughout growth. Supplementation with exogenous putrescine or spermidine during polyamine starvation (late log phase) results in increased conjugate levels (> 74% of total glutathione) and is associated with large increases in total putrescine and spermidine. Likewise, supplementation with exogenous cadaverine and aminopropylcadaverine results in similar increases in trypanothione analogues and total cadaverine and aminopropylcadaverine. In contrast, ornithine, arginine, lysine, agmatine and other amino acid precursors have no effect on polyamine or conjugate levels. No significant ornithine or arginine decarboxylase activities could be detected (< 0.8 pmol min(-1) [mg protein](-1)). Similar results were obtained for epimastigotes representing all the major zymodeme classes, providing evidence that diamine auxotrophy may be a universal feature of this stage of the life-cycle. Copyright (C) 1997 Elsevier Science B.V.