Trypanosomes lacking trypanothione reductase are avirulent and show increased sensitivity to oxidative stress

被引:300
作者
Krieger, S
Schwarz, W
Ariyanayagam, MR
Fairlamb, AH
Krauth-Siegel, RL
Clayton, C
机构
[1] Heidelberg Univ, Zentrum Mol Biol, D-69120 Heidelberg, Germany
[2] Univ Dundee, Dept Biochem, Dundee DD1 5EH, Scotland
[3] Heidelberg Univ, Zentrum Biochem, D-69120 Heidelberg, Germany
关键词
D O I
10.1046/j.1365-2958.2000.01721.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
In Kinetoplastida, trypanothione and trypanothione reductase (TRYR) provide an intracellular reducing environment, substituting for the glutathione-glutathione reductase system found in most other organisms. To investigate the physiological role of TRYR in Trypanosoma brucei, we generated cells containing just one trypanothione reductase gene, TRYR, which was under the control of a tetracycline-inducible promoter. This enabled us to regulate TRYR activity in the cells from less than 1% to 400% of wild-type levels by adjusting the concentration of added tetracycline. In normal growth medium (which contains reducing agents), trypanosomes containing less than 10% of wild-type enzyme activity were unable to grow, although the levels of reduced trypanothione and total thiols remained constant. In media lacking reducing agents, hypersensitivity towards hydrogen peroxide (EC50 = 3.5 mu M) was observed compared with the wild type (EC50 = 223 mu M). The depletion of TRYR had no effect on susceptibility to melarsen oxide. The infectivity and virulence of the parasites in mice was dependent upon tetracycline-regulated TRYR activity: if the trypanosomes were injected into mice in the absence of tetracycline, no infection was detectable; and when tetracycline was withdrawn from previously infected animals, the parasitaemia was suppressed.
引用
收藏
页码:542 / 552
页数:11
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