Comprehensive Characterization of Toxoplasma Acyl Coenzyme A-Binding Protein TgACBP2 and Its Critical Role in Parasite Cardiolipin Metabolism.
Comprehensive Characterization of Toxoplasma Acyl Coenzyme A-Binding Protein TgACBP2 and Its Critical Role in Parasite Cardiolipin Metabolism.
复制标题
弓形虫酰基辅酶 A 结合蛋白 TgACBP2 的综合表征及其在寄生虫心磷脂代谢中的关键作用
作者：
Fu Y;Cui X;Fan S;Liu J;Zhang X;Wu Y;Liu Q
刚地弓形虫是最成功的人类寄生虫之一，感染了世界总人口的近三分之一。寄生液泡（pv）内的弓形虫速殖子既可以通过从宿主细胞中获取脂肪酸，也可以通过重新合成途径获得膜生物生成所需的脂肪酸。然而，尽管已知这种寄生虫中存在脂肪酸通量，但脂肪酸如何流经弓形虫脂质代谢细胞器，特别是线粒体，仍然未知。在这项研究中，我们证明弓形虫表达含有TgACBP2蛋白的活性锚蛋白重复序列来协调心磷脂代谢。具体来说，MAF1异种功能性表达导致的HMA获取挽救了acbp2缺失型II型寄生虫的生长和脂质代谢缺陷，表明宿主线粒体在寄生虫心磷脂代谢中的互补作用。这项工作强调了TgACBP2在寄生虫心磷脂代谢中的重要性，并为宿主线粒体与弓形虫的代谢关联提供了证据。酰基辅酶A （CoA）结合蛋白（ACBP）能以高特异性和亲和力结合酰基辅酶A，在细胞功能中发挥多种作用。刚地弓形虫的线粒体已成为脂质代谢和信号转导的关键细胞器。然而，这种寄生虫如何利用酰基辅酶a结合蛋白调节线粒体脂质代谢的基本原理仍不清楚。在这里，我们发现含有锚蛋白重复序列的蛋白TgACBP2定位于线粒体，并表现出活跃的酰基辅酶a结合活性。TgACBP2的去磷酸化与在环境调控条件下从质膜向线粒体的迁移有关[K+]。在高[K+]条件下，ACBP2的缺失导致线粒体功能障碍和细胞凋亡样死亡。破坏ACBP2导致II型菌株生长和毒力缺陷，但在I型寄生虫中没有。有趣的是，线粒体关联因子-1 （MAF1）介导的宿主线粒体关联（HMA）恢复了acbp2缺陷型II型寄生虫的生长能力。脂质组学分析表明，ACBP2在II型寄生虫的心磷脂代谢中起关键作用，MAF1的表达弥补了ACBP2缺失的II型寄生虫的脂质代谢缺陷。此外，ACBP2的破坏导致Pru寄生虫对小鼠的毒力减弱。综上所述，这些数据表明ACBP2在高[K+]条件下对II型寄生虫和I型寄生虫的生长和毒力至关重要。
Toxoplasma gondii is one of the most successful human parasites, infecting nearly one-third of the total world population. T. gondii tachyzoites residing within parasitophorous vacuoles (PVs) can acquire fatty acids both via salvage from host cells and via de novo synthesis pathways for membrane biogenesis. However, although fatty acid fluxes are known to exist in this parasite, how fatty acids flow through Toxoplasma lipid metabolic organelles, especially mitochondria, remains unknown. In this study, we demonstrated that Toxoplasma expresses an active ankyrin repeat containing protein TgACBP2 to coordinate cardiolipin metabolism. Specifically, HMA acquisition resulting from heterologous functional expression of MAF1 rescued growth and lipid metabolism defects in ACBP2-deficient type II parasites, manifesting the complementary role of host mitochondria in parasite cardiolipin metabolism. This work highlights the importance of TgACBP2 in parasite cardiolipin metabolism and provides evidence for metabolic association of host mitochondria with T. gondii. Acyl coenzyme A (CoA)-binding protein (ACBP) can bind acyl-CoAs with high specificity and affinity, thus playing multiple roles in cellular functions. Mitochondria of the apicomplexan parasite Toxoplasma gondii have emerged as key organelles for lipid metabolism and signaling transduction. However, the rationale for how this parasite utilizes acyl-CoA-binding protein to regulate mitochondrial lipid metabolism remains unclear. Here, we show that an ankyrin repeat-containing protein, TgACBP2, is localized to mitochondria and displays active acyl-CoA-binding activities. Dephosphorylation of TgACBP2 is associated with relocation from the plasma membrane to the mitochondria under conditions of regulation of environmental [K+]. Under high [K+] conditions, loss of ACBP2 induced mitochondrial dysfunction and apoptosis-like cell death. Disruption of ACBP2 caused growth and virulence defects in the type II strain but not in type I parasites. Interestingly, mitochondrial association factor-1 (MAF1)-mediated host mitochondrial association (HMA) restored the growth ability of ACBP2-deficient type II parasites. Lipidomics analysis indicated that ACBP2 plays key roles in the cardiolipin metabolism of type II parasites and that MAF1 expression complemented the lipid metabolism defects of ACBP2-deficient type II parasites. In addition, disruption of ACBP2 caused attenuated virulence of Prugniuad (Pru) parasites for mice. Taking the results collectively, these data indicate that ACBP2 is critical for the growth and virulence of type II parasites and for the growth of type I parasites under high [K+] conditions.