Malaria parasite harbors a unique protein lysine methyltransferase targeting both chromatin and motility machinery

项目总结 表观遗传学机制已被用作重要的治疗药物靶点，这一点从 成功的癌症治疗抑制剂。尽管疟疾寄生虫有许多表观遗传学 监管者，发现与人类不同的独特基因仍然是一个巨大的挑战 主持人。根据以前的研究和我们最近的初步数据，PfSET7，十个集合域之一 在恶性疟原虫中发现含有赖氨酸(K)甲基转移酶(KMTs)的 疟原虫特异的KMT具有独特的结构和功能。PfSET7不属于任何 在模式生物中已知的SET家族，因为它在SET结构域中包含唯一的基序II。 PfSET7定位于裂殖子顶端，PfSET7下调约35% 使用我们新开发的CRISPR干扰(CRISPRi)导致裂殖子缺陷 出口和入侵，让人想起国民党弓形虫根尖复合体的发现 (TgAKMT)在脱出和破坏TgAKMT导致缺陷之前也定位在根尖 在寄生虫的外泄和入侵中，由于运动能力受损。然而，TgAKMT的行动模式， 尤其是它的底物，仍然是未知的。值得注意的是，PfSET7也被发现定位于 配子细胞质和核，以及PfSET7基因下调~26%也导致缺陷 在配子体发育中，与PfSET7在 配子体和许多不同的甲基化赖氨酸存在于配子体组蛋白中。 值得注意的是，PfSET7包含四个疟原虫特异性区域，与 TgAKMT，表明PfSET7含有疟疾特异性结构。基于这些发现，我们 假设PfSET7是疟原虫特异的KMT，并具有双重调控功能 靶向组蛋白对配子体基因表达和裂殖子运动的影响 和非组蛋白。破译关键功能和底物专一性 对于PfSET7，我们将应用先进的新技术，包括更强大的CRISPRi KD 优化的gRNA和用于基因功能研究的条件敲除，以及定量 用于底物鉴定的甲基组。预计这项研究将为 理解PfSET7的S作用机制和新型顶端复合体的开发 特定的表观遗传药物。

PROJECT SUMMARY Epigenetics machinery has been used as important therapeutic drug targets evident by the successful inhibitors for cancer treatment. Although the malaria parasite harbors many epigenetic regulators, it remains a great challenge to discover unique ones diverse from those in the human host. Based on previous studies and our recent preliminary data, PfSET7, one of ten SET-domain containing lysine (K) methyltransferases (KMTs) in Plasmodium falciparum, is discovered to be a Plasmodium-specific KMT with unique structures and functions. PfSET7 does not belong to any known SET family in model organisms because it contains a unique motif II in the SET domain. PfSET7 was found localized at the apical tip of merozoite and downregulation of PfSET7 by ~35% using our newly developed CRISPR interference (CRISPRi) resulted in defects in merozoite egress and invasion, reminiscent of the findings that Toxoplasma gondii apical complex KMT (TgAKMT) is also localized at the apical tip before egress and disruption of TgAKMT led to defects in parasite egress and invasion due to impaired motility. However, TgAKMT’s mode of action, especially its substrates, is still unknown. Remarkably, PfSET7 was found also localized in the gametocyte cytoplasm and nucleus, and downregulation of PfSET7 by ~26% also led to defects in gametocyte development, coincidentally with the findings that PfSET7 has peak expression in gametocytes and many distinct methylated lysines were identified in gametocyte histones. Notably, PfSET7 contains four Plasmodium-specific regions and is only ~41% identical to TgAKMT, indicating PfSET7 harbors malaria-specific structures. Based on these findings, we hypothesize that PfSET7 is a Plasmodium-specific KMT and has a dual function in the regulation of gametocyte gene expression and merozoite motility during egress/invasion by targeting histone and non-histone proteins, respectively. To decipher the critical function and substrate specificity of PfSET7, we will apply advanced new technologies including a stronger CRISPRi KD with optimized gRNAs and a conditional knockout for gene functional study, and quantitative methylome for substrate identification. It is anticipated that this study will lay a solid foundation for understanding PfSET7’s mechanism of action and the development of novel apicomplexan- specific epigenetic drugs.