The human malaria parasite Plasmodium falciparum encodes a single ortholog of heterochromatin protein 1 (PfHP1) that plays a crucial role in the epigenetic regulation of various survival-related processes. PfHP1 is essential for parasite proliferation and the heritable silencing of genes linked to antigenic variation, host cell invasion, and sexual conversion. Here, we employed CRISPR/Cas9-mediated genome editing combined with the DiCre/loxP system to investigate how the PfHP1 chromodomain (CD), hinge domain, and chromoshadow domain (CSD) contribute to overall PfHP1 function. We show that the 76 C-terminal residues are responsible for targeting PfHP1 to the nucleus. Furthermore, we reveal that each of the three functional domains of PfHP1 are required for heterochromatin formation, gene silencing, and mitotic parasite proliferation. Finally, we discovered that the hinge domain and CSD of HP1 are functionally conserved between P. falciparum and P. berghei, a related malaria parasite infecting rodents. In summary, our study provides new insights into PfHP1 function and offers a tool for further studies on epigenetic regulation and life cycle decision in malaria parasites.

中文翻译：

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使用条件结构域删除和交换方法研究异染色质蛋白 1 在疟原虫恶性疟原虫中的功能


人类疟原虫恶性疟原虫编码异染色质蛋白 1 (PfHP1) 的单一直系同源物，该蛋白在各种生存相关过程的表观遗传调控中发挥着至关重要的作用。 PfHP1 对于寄生虫增殖以及与抗原变异、宿主细胞入侵和性转变相关的基因的可遗传沉默至关重要。在这里，我们采用 CRISPR/Cas9 介导的基因组编辑结合 DiCre/loxP 系统来研究 PfHP1 染色结构域 (CD)、铰链结构域和染色阴影结构域 (CSD) 如何影响 PfHP1 的整体功能。我们发现 76 个 C 端残基负责将 PfHP1 靶向细胞核。此外，我们揭示了 PfHP1 的三个功能域中的每一个都是异染色质形成、基因沉默和有丝分裂寄生虫增殖所必需的。最后，我们发现 HP1 的铰链结构域和 CSD 在恶性疟原虫和伯氏疟原虫（一种感染啮齿动物的相关疟原虫）之间功能保守。总之，我们的研究提供了对 PfHP1 功能的新见解，并为进一步研究疟疾寄生虫的表观遗传调控和生命周期决策提供了工具。