Liburkin-Dan T, Schlisselberg D, Fischer-Weinberger R, Pescher P, Inbar E, Ephros M, Rentsch D, Späth G F, Zilberstein D
Faculty of Biology, Technion - Israel Institute of Technology, Haifa 3200003, Haifa, Israel.
Institut Pasteur, INSERM U1201, Unité de Parasitologie moléculaire et Signalisation, 75015 Paris, France.
Mol Biochem Parasitol. 2018 Jun;222:1-5. doi: 10.1016/j.molbiopara.2018.04.002. Epub 2018 Apr 12.
Leishmania are obligatory intracellular parasites that cycle between the sand fly midgut (extracellular promastigotes) and mammalian macrophage phagolysosomes (intracellular amastigotes). They have developed mechanisms of adaptation to the distinct environments of host and vector that favor utilization of both proline and alanine. LdAAP24 is the L. donovani proline-alanine transporter. It is a member of Leishmania system A that translocates neutral amino acids. Since system A is promastigote-specific, we aimed to assess whether LdAAP24 is also expressed exclusively in promastigotes. Herein, we established that upon exposing L. donovani promastigotes to amastigote differentiation signal (pH 5.5 and 37 °C), parasites rapidly and completely degrade LdAAP24 protein in both axenic and in spleen-derived amastigotes. In contrast, LdAAP24 mRNA remained unchanged throughout differentiation. Addition of either MG132 or Bafilomycin A1 partially inhibited LdAAP24 protein degradation, indicating a role for both lysosome- and proteasome-mediated degradation. This work provides the first evidence for post-translational regulation of stage-specific expression of LdAAP24.
利什曼原虫是专性细胞内寄生虫，在沙蝇中肠（细胞外前鞭毛体）和哺乳动物巨噬细胞吞噬溶酶体（细胞内无鞭毛体）之间循环。它们已经形成了适应宿主和载体不同环境的机制，有利于利用脯氨酸和丙氨酸。LdAAP24是杜氏利什曼原虫的脯氨酸 - 丙氨酸转运蛋白。它是利什曼原虫系统A的成员，该系统转运中性氨基酸。由于系统A是前鞭毛体特异性的，我们旨在评估LdAAP24是否也仅在前鞭毛体中表达。在此，我们确定，将杜氏利什曼原虫前鞭毛体暴露于无鞭毛体分化信号（pH 5.5和37°C）后，寄生虫在体外培养的无鞭毛体和脾脏来源的无鞭毛体中迅速且完全降解LdAAP24蛋白。相比之下，LdAAP24 mRNA在整个分化过程中保持不变。添加MG132或巴弗洛霉素A1部分抑制LdAAP24蛋白降解，表明溶酶体和蛋白酶体介导的降解都起作用。这项工作为LdAAP24阶段特异性表达的翻译后调控提供了首个证据。
