The role of Plasmodium falciparum food vacuole plasmepsins
The role of Plasmodium falciparum food vacuole plasmepsins
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DOI：
10.1074/jbc.m409740200
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发表时间：
2005-01-14
影响因子：
4.8
通讯作者：
Goldberg, DE
中科院分区：
文献类型：
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作者：
Liu, J;Gluzman, IY;Goldberg, DE
纤溶酶（PM）被认为在疟原虫恶性疟原虫的血红蛋白降解中具有重要功能，并且作为抗疟药物靶点引起了人们的兴趣。四种旁系同源血浆蛋白酶存在于恶性疟原虫的食物液泡中。通过双交换同源重组进行的靶向基因破坏已用于研究培养寄生虫中的食物泡血浆蛋白酶功能。已经生成了 PM I、PM II 和 HAP 基因均缺失的寄生虫克隆以及 PM IV/PM I 双破坏的克隆。所有这些克隆都缺乏相应的 PM，具有活力，并且形态正常。 PM II 和 PM IV/I 中断在丰富的 RPMI 培养基中比 3D7 亲本系具有更长的倍增时间。这似乎是因为生产性后代水平下降，而不是细胞周期时间增加。在氨基酸限制培养基中，所有四种基因敲除菌株均表现出比亲本菌株更慢的生长。与 3D7 相比，敲除克隆对天冬氨酸和半胱氨酸蛋白酶抑制剂的敏感性变化最小。这些结果表明存在大量的功能冗余，并对抗疟药物的设计具有重要意义。缓慢生长的表型可以解释为什么恶性疟原虫保留了四个具有重叠功能的血浆蛋白酶基因。
Plasmepsins (PMs) are thought to have an important function in hemoglobin degradation in the malarial parasite Plasmodium falciparum and have generated interest as antimalarial drug targets. Four paralogous plasmepsins reside in the food vacuole of P. falciparum. Targeted gene disruption by double crossover homologous recombination has been employed to study food vacuole plasmepsin function in cultured parasites. Parasite clones with deletions in each of the individual PM I, PM II, and HAP genes as well as clones with a double PM IV/PM I disruption have been generated. All of these clones lack the corresponding PMs, are viable, and appear morphologically normal. PM II and PM IV/I disruptions have longer doubling times than the 3D7 parental line in rich RPMI medium. This appears to be because of a decreased level of productive progeny rather than an increased cell cycle time. In amino acid-limited medium, all four knockouts exhibit slower growth than the parental strain. Compared with 3D7, knock-out clone sensitivity to aspartic and cysteine protease inhibitors is changed minimally. These results suggest substantial functional redundancy and have important implications for the design of antimalarial drugs. The slow growth phenotype may explain why P. falciparum has maintained four plasmepsin genes with overlapping functions.