The protozoan parasite Leishmania donovani is part of an early eukaryotic branch and depends on post-transcriptional mechanisms for gene expression regulation. This includes post-transcriptional protein modifications, such as protein phosphorylation. The presence of genes for protein SUMOylation, i.e., the covalent attachment of small ubiquitin-like modifier (SUMO) polypeptides, in the Leishmania genomes prompted us to investigate the importance of the sentrin-specific protease (SENP) and its putative client, SUMO, for the vitality and infectivity of Leishmania donovani. While SENP null mutants are viable with reduced vitality, viable SUMO null mutant lines could not be obtained. SUMO C-terminal processing is disrupted in SENP null mutants, preventing SUMO from covalent attachment to proteins and nuclear translocation. Infectivity in vitro is not affected by the loss of SENP-dependent SUMO processing. We conclude that SENP is required for SUMO processing, but that functions of unprocessed SUMO are critical for Leishmania viability.

中文翻译：

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SUMO 处理需要杜氏利什曼原虫 SENP 蛋白酶，但活性不需要


原生动物寄生虫杜氏利什曼原虫是早期真核分支的一部分，依赖于基因表达调控的转录后机制。这包括转录后蛋白质修饰，例如蛋白质磷酸化。利什曼原虫基因组中蛋白质 SUMO 化（即小泛素样修饰剂 (SUMO) 多肽的共价连接）基因的存在促使我们研究哨蛋白特异性蛋白酶 (SENP) 及其假定客户 SUMO 的重要性。杜氏利什曼原虫的活力和传染性。虽然 SENP 无效突变体在活力降低的情况下是可行的，但无法获得可行的 SUMO 无效突变体系。 SUMO C 末端加工在 SENP 无效突变体中被破坏，从而阻止 SUMO 与蛋白质共价连接和核转位。体外感染性不受 SENP 依赖性 SUMO 处理丧失的影响。我们的结论是 SENP 是 SUMO 处理所必需的，但未处理的 SUMO 的功能对于利什曼原虫的生存能力至关重要。