C-Terminal Mutants of Apolipoprotein L-I Efficiently Kill Both Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense
C-Terminal Mutants of Apolipoprotein L-I Efficiently Kill Both Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense
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DOI：
10.1371/journal.ppat.1000685
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发表时间：
2009-12-01
期刊：
影响因子：
6.7
通讯作者：
Pays, Etienne
中科院分区：
文献类型：
--
作者：
Lecordier, Laurence;Vanhollebeke, Benoit;Pays, Etienne
载脂蛋白L-I （apoL1）是一种人类特异性血清蛋白，通过在寄生虫内体膜上形成离子孔杀死布鲁氏锥虫。布氏锥虫亚种罗得西亚锥虫和冈比亚锥虫能抵抗这种分解活性，并能感染人类，引起昏睡病。在罗得西亚锥虫的情况下，对裂解的抗性涉及血清抗性相关（SRA）蛋白与apoL1的c端螺旋的相互作用。我们对apoL1的c端螺旋进行了突变和缺失分析，以研究与SRA的相互作用与不同布鲁氏T.亚种的裂解潜力之间的联系。我们确认c端螺旋是sra相互作用的结构域。虽然在大肠杆菌中，该结构域对于离子孔形成活性是必不可少的，但它与SRA的相互作用导致了该活性的抑制。影响c端螺旋的不同突变降低了apoL1与SRA的相互作用。然而，L370-L392亮氨酸拉链的突变体也失去了体外胰蛋白酶水解活性。截断和/或突变人类apoL1的c端序列，就像Papio anubis的apoL1样序列一样，导致与SRA的相互作用丧失，并获得了在体外和转基因小鼠中有效杀死人类血清耐药罗得西亚锥虫的能力。这些发现表明SRA与apoL1 c端螺旋的相互作用抑制了其成孔活性，并决定了罗得西亚锥虫对人血清的抗性。此外，它们为Papio血清杀死布氏布氏锥虫的能力提供了可能的解释，并为产生对布氏布氏锥虫和布氏布氏锥虫具有抗性的转基因牛提供了一个视角。
Apolipoprotein L-I (apoL1) is a human-specific serum protein that kills Trypanosoma brucei through ionic pore formation in endosomal membranes of the parasite. The T. brucei subspecies rhodesiense and gambiense resist this lytic activity and can infect humans, causing sleeping sickness. In the case of T. b. rhodesiense, resistance to lysis involves interaction of the Serum Resistance-Associated (SRA) protein with the C-terminal helix of apoL1. We undertook a mutational and deletional analysis of the C-terminal helix of apoL1 to investigate the linkage between interaction with SRA and lytic potential for different T. brucei subspecies. We confirm that the C-terminal helix is the SRA-interacting domain. Although in E. coli this domain was dispensable for ionic pore-forming activity, its interaction with SRA resulted in inhibition of this activity. Different mutations affecting the C-terminal helix reduced the interaction of apoL1 with SRA. However, mutants in the L370-L392 leucine zipper also lost in vitro trypanolytic activity. Truncating and/or mutating the C-terminal sequence of human apoL1 like that of apoL1-like sequences of Papio anubis resulted in both loss of interaction with SRA and acquired ability to efficiently kill human serum-resistant T. b. rhodesiense parasites, in vitro as well as in transgenic mice. These findings demonstrate that SRA interaction with the C-terminal helix of apoL1 inhibits its pore-forming activity and determines resistance of T. b. rhodesiense to human serum. In addition, they provide a possible explanation for the ability of Papio serum to kill T. b. rhodesiense, and offer a perspective to generate transgenic cattle resistant to both T. b. brucei and T. b. rhodesiense.