A leucine aminopeptidase is involved in kinetoplast DNA segregation in Trypanosoma brucei.
A leucine aminopeptidase is involved in kinetoplast DNA segregation in Trypanosoma brucei.
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DOI：
10.1371/journal.ppat.1006310
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发表时间：
2017-04
期刊：
影响因子：
6.7
通讯作者：
Lukeš J
中科院分区：
文献类型：
--
作者：
Peña-Diaz P;Vancová M;Resl C;Field MC;Lukeš J
动质体（k）是锥虫原生生物独特包装的线粒体DNA，由每个细胞周期分裂和分离一次的小环和大环的链状网络形成。尽管现在已知许多参与kDNA复制和分离的蛋白质，但复制机制中的几个关键步骤在分子水平上仍未得到表征，其中之一是nabelschnur或脐，这是哺乳动物寄生虫布氏锥虫中的一个重要结构。在子kDNA网络分离之前连接它们。在这里，我们表征M17家族亮氨酰氨肽酶金属蛋白酶，称为TbLAP 1，它特异性地定位于kDNA盘和nabelschur，并代表在这种结构中发现的第一个描述的蛋白质。我们发现，TbLAP 1是正确的分离kDNA所必需的，敲低导致延迟的胞质分裂和异位表达，导致kDNA丢失和细胞增殖减少。我们认为TbLAP 1是有效的kDNA分裂所必需的，并且专门参与子kDNA网络的分离。锥虫带有一个单一的染色体，其基因组（动质体，或kDNA）排列成环状分子的网络。kDNA对于布氏锥虫的生命周期是必不可少的，因为它是昆虫载体的正常功能和通过昆虫载体的进展所必需的。kDNA的分裂与核DNA的复制和额外的细胞周期事件同步。虽然kDNA复制的机制是很好的理解和蛋白质介导的这一过程中确定，几个关键步骤，包括隔离，仍然知之甚少，部分原因是由于缺乏特征蛋白质在这个阶段的具体功能。在这里，我们报告亮氨酸氨肽酶1（LAP 1）作为第一个确定的组成部分的nabelschnur，或脐，在分离的女儿kDNA网络，其表达是正确的动质体分离所需的结构。
The kinetoplast (k), the uniquely packaged mitochondrial DNA of trypanosomatid protists is formed by a catenated network of minicircles and maxicircles that divide and segregate once each cell cycle. Although many proteins involved in kDNA replication and segregation are now known, several key steps in the replication mechanism remain uncharacterized at the molecular level, one of which is the nabelschnur or umbilicus, a prominent structure which in the mammalian parasite Trypanosoma brucei connects the daughter kDNA networks prior to their segregation. Here we characterize an M17 family leucyl aminopeptidase metalloprotease, termed TbLAP1, which specifically localizes to the kDNA disk and the nabelschur and represents the first described protein found in this structure. We show that TbLAP1 is required for correct segregation of kDNA, with knockdown resulting in delayed cytokinesis and ectopic expression leading to kDNA loss and decreased cell proliferation. We propose that TbLAP1 is required for efficient kDNA division and specifically participates in the separation of daughter kDNA networks. Trypanosomes bear a single mitochondrion with its genome (kinetoplast, or kDNA) arranged as a network of circular molecules. kDNA is essential for the Trypanosoma brucei life cycle, as it is required for proper functioning of the mitochondrion and progression through the insect vector. Division of kDNA is synchronized with the replication of nuclear DNA and additional cell cycle events. Though the mechanism of kDNA replication is well understood and proteins mediating this process identified, several key steps, including segregation, remain poorly known, in part due to the absence of characterized proteins specifically functioning at this stage. Here we report leucine aminopeptidase 1 (LAP1) as the first identified component of the nabelschnur, or umbilicus, a structure observed during the separation of daughter kDNA networks, whose expression is required for correct kinetoplast segregation.