Kinetics of S-adenosylmethionine cellular transport and protein methylation in Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense.
Kinetics of S-adenosylmethionine cellular transport and protein methylation in Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense.
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布氏锥虫和罗德西亚布氏锥虫中 S-腺苷甲硫氨酸细胞转运和蛋白质甲基化的动力学。
DOI：
10.1006/abbi.1999.1098
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Bacchi,CJ
中科院分区：
文献类型：
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作者：
Goldberg,B;Rattendi,D;Lloyd,D;Yarlett,N;Bacchi,CJ
布氏锥虫属的非洲锥虫是人类和动物疾病的病原体。它们具有独特的生化特征，如需要预先形成的嘌呤，并具有广泛的核苷回收补救机制。在这方面，我们已经表明，锥虫有一个专门的转运S-腺苷甲硫氨酸（蛋氨酸），在转甲基化反应和多胺合成的关键代谢产物。在这项研究中，我们比较了表观动力学的cDNAMet运输，胞质cDNAMet池的形成，并利用cDNAMet在蛋白质甲基化反应中使用两个分离株：布氏锥虫布氏锥虫，一种兽医寄生虫，和布氏锥虫罗得西亚，一种人类病原体，是高度难治性，并大大降低了敏感性标准的杀锥虫剂活性againstT。B.用Hanes-Woolf分析法计算了T. brucei. B.布氏杆菌对T. B. Rhodesiense，Vmax分别为124和400 μ mol/L/min。两种菌株都形成了大量的AdoMet胞浆池，1600 nmol/109 T。B. 3500 nmol/109 T. B.用25 mM外源性蛋氨酸孵育10 min后，从用[甲基-3 H]蛋氨酸孵育的细胞的洗涤的三氯乙酸沉淀物获得的数据表明，T. B.布氏杆菌是T. B的4倍。这些结果表明，非洲锥虫独特的快速摄取和利用Rhodesiense是设计和开发可能用于化疗的新试剂的重要考虑因素。
African trypanosomes of theTrypanosoma bruceigroup are agents of disease in man and animals. They present unique biochemical characteristics such as the need for preformed purines and have extensive salvage mechanisms for nucleoside recovery. In this regard we have shown that trypanosomes have a dedicated transporter forS-adenosylmethionine (AdoMet), a key metabolite in transmethylation reactions and polyamine synthesis. In this study we compared the apparent kinetics of AdoMet transport, cytosolic AdoMet pool formation, and utilization of AdoMet in protein methylation reactions using two isolates:Trypanosoma brucei brucei,a veterinary parasite, andTrypanosoma brucei rhodesiense,a human pathogen that is highly refractory and has greatly reduced susceptibility to standard trypanocidal agents active againstT. b. brucei.The apparentKmvalues for [methyl-3H]AdoMet transport, derived by Hanes–Woolf analysis, forT. b. bruceiwas 4.2 and 10 mM forT. b. rhodesiense,and theVmaxvalues were 124 and 400 μmol/liter/min, respectively. Both strains formed substantial cytosolic pools of AdoMet, 1600 nmol/109T. b. bruceiand 3500 nmol/109T. b. rhodesienseafter 10 min incubation with 25 mM exogenous AdoMet. Data obtained from washed trichloroacetic acid precipitates of cells incubated with [methyl-3H]AdoMet indicated that the rate of protein methylation inT. b. bruceiwas fourfold greater than inT. b. rhodesiense.These results demonstrate that the unique rapid uptake and utilization of AdoMet by African trypanosomes is an important consideration in the design and development of new agents of potential use in chemotherapy.