4.6 Article

Kinetic studies reveal a key role of a redox-active glutaredoxin in the evolution of the thiol-redox metabolism of trypanosomatid parasites

期刊

JOURNAL OF BIOLOGICAL CHEMISTRY
卷 294, 期 9, 页码 3235-3248

出版社

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA118.006366

关键词

trypanosome; glutathionylation; oxidation-reduction (redox); enzyme catalysis; disulfide; thiol; fluorescence; trypanothione

资金

  1. Comision Sectorial de Investigacion Cientifica Universidad de la Republica [C601-348]
  2. International Centre for Genetic Engineering and Biotechnology [CRP/URU14-01]
  3. PRAT Universita degli Studi di Padova [COF 03/11, CPDA137397/13]
  4. European Comission [261863]
  5. Fondo para la Convergencia Estructural del Mercosur

向作者/读者索取更多资源

Trypanosomes are flagellated protozoan parasites (kinetoplastids) that have a unique redox metabolism based on the small dithiol trypanothione (T(SH)(2)). Although GSH may still play a biological role in trypanosomatid parasites beyond being a building block of T(SH)(2), most of its functions are replaced by T(SH)(2) in these organisms. Consequently, trypanosomes have several enzymes adapted to using T(SH)(2) instead of GSH, including the glutaredoxins (Grxs). However, the mechanistic basis of Grx specificity for T(SH)(2) is unknown. Here, we combined fast-kinetic and biophysical approaches, including NMR, MS, and fluorescent tagging, to study the redox function of Grx1, the only cytosolic redox-active Grx in trypanosomes. We observed that Grx1 reduces GSH-containing disulfides (including oxidized trypanothione) in very fast reactions (k > 5 x 10(5) m(-1) s(-1)). We also noted that disulfides without a GSH are much slower oxidants, suggesting a strongly selective binding of the GSH molecule. Not surprisingly, oxidized Grx1 was also reduced very fast by T(SH)(2) (4.8 x 10(6) m(-1) s(-1)); however, GSH-mediated reduction was extremely slow (39 m(-1) s(-1)). This kinetic selectivity in the reduction step of the catalytic cycle suggests that Grx1 uses preferentially a dithiol mechanism, forming a disulfide on the active site during the oxidative half of the catalytic cycle and then being rapidly reduced by T(SH)(2) in the reductive half. Thus, the reduction of glutathionylated substrates avoids GSSG accumulation in an organism lacking GSH reductase. These findings suggest that Grx1 has played an important adaptive role during the rewiring of the thiol-redox metabolism of kinetoplastids.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.6
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据