Replication and partitioning of the apicoplast genome of Toxoplasma gondii is linked to the cell cycle and requires DNA polymerase and gyrase.
Replication and partitioning of the apicoplast genome of Toxoplasma gondii is linked to the cell cycle and requires DNA polymerase and gyrase.
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DOI：
10.1016/j.ijpara.2020.11.004
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发表时间：
2021-05
影响因子：
4
通讯作者：
Striepen B
中科院分区：
文献类型：
--
作者：
Martins-Duarte ÉS;Sheiner L;Reiff SB;de Souza W;Striepen B
DNA 复制酶 Prex、DNA 旋转酶和 DNA 单链结合蛋白定位于弓形虫顶质体。 DNA 旋转酶 A 和 B 以及 Prex 是顶端质体基因组复制和寄生虫生长所必需的。顶质体核的分裂和分离在 S 期开始时开始，并在有丝分裂期间结束。顶质体核的复制和分裂与核基因组复制和有丝分裂高度协调。顶复菌是许多重要传染病的病原体，包括疟疾和弓形体病。它们中的大多数都含有一种类似叶绿体的细胞器，称为顶端质体，这对于寄生虫的新陈代谢和生存至关重要。虽然大多数顶质体蛋白是核编码的，但细胞器也保留自己的基因组，即一个 35 kb 的环。在这项研究中，我们使用弓形虫来鉴定和表征参与顶质体基因组复制的必需蛋白质，并了解顶质体基因组分离如何随着时间的推移而展开。我们证明 DNA 复制酶 Prex、DNA 旋转酶和 DNA 单链结合蛋白定位于顶质体。我们在敲除实验中表明，顶质体 DNA 旋转酶 A 和 B 以及 Prex 是顶质体基因组复制和寄生虫生长所必需的。通过结构照明显微镜对弓形虫速殖子中顶质体基因组复制进行的分析表明，顶质体核分裂和分离在S期开始时开始并在有丝分裂期间结束。因此，顶质体核的复制和分裂与核基因组复制和有丝分裂高度协调。我们的观察强调了顶端质体基因组维持的重要组成部分，并揭示了在整个寄生虫细胞周期的背景下这一过程的时间安排。
DNA replication enzymes Prex, DNA gyrase and DNA single stranded binding protein localise to the Toxoplasma gondii apicoplast. DNA Gyrase A and B and Prex are required for apicoplast genome replication and the growth of the parasite. Apicoplast nucleoid division and segregation initiate at the beginning of the S phase and conclude during mitosis. Replication and division of the apicoplast nucleoid is highly coordinated with nuclear genomic replication and mitosis. Apicomplexans are the causative agents of numerous important infectious diseases including malaria and toxoplasmosis. Most of them harbour a chloroplast-like organelle called the apicoplast that is essential for the parasites’ metabolism and survival. While most apicoplast proteins are nuclear encoded, the organelle also maintains its own genome, a 35 kb circle. In this study we used Toxoplasma gondii to identify and characterise essential proteins involved in apicoplast genome replication and to understand how apicoplast genome segregation unfolds over time. We demonstrated that the DNA replication enzymes Prex, DNA gyrase and DNA single stranded binding protein localise to the apicoplast. We show in knockdown experiments that apicoplast DNA Gyrase A and B, and Prex are required for apicoplast genome replication and growth of the parasite. Analysis of apicoplast genome replication by structured illumination microscopy in T. gondii tachyzoites showed that apicoplast nucleoid division and segregation initiate at the beginning of S phase and conclude during mitosis. Thus, the replication and division of the apicoplast nucleoid is highly coordinated with nuclear genome replication and mitosis. Our observations highlight essential components of apicoplast genome maintenance and shed light on the timing of this process in the context of the overall parasite cell cycle.
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