The Walter and Eliza Hall Institute of Medical Research, 1 G Royal Parade, Parkville, VIC, 3052, Australia.
Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia.
Nat Commun. 2022 Jul 29;13(1):4400. doi: 10.1038/s41467-022-32076-8.
Tryptophan C-mannosylation stabilizes proteins bearing a thrombospondin repeat (TSR) domain in metazoans. Here we show that Plasmodium falciparum expresses a DPY19 tryptophan C-mannosyltransferase in the endoplasmic reticulum and that DPY19-deficiency abolishes C-glycosylation, destabilizes members of the TRAP adhesin family and inhibits transmission to mosquitoes. Imaging P. falciparum gametogenesis in its entirety in four dimensions using lattice light-sheet microscopy reveals defects in ΔDPY19 gametocyte egress and exflagellation. While egress is diminished, ΔDPY19 microgametes still fertilize macrogametes, forming ookinetes, but these are abrogated for mosquito infection. The gametogenesis defects correspond with destabilization of MTRAP, which we show is C-mannosylated in P. falciparum, and the ookinete defect is concordant with defective CTRP secretion on the ΔDPY19 background. Genetic complementation of DPY19 restores ookinete infectivity, sporozoite production and C-mannosylation activity. Therefore, tryptophan C-mannosylation by DPY19 ensures TSR protein quality control at two lifecycle stages for successful transmission of the human malaria parasite.
色氨酸 C-甘露糖基化稳定了后生动物中具有血栓素重复（TSR）结构域的蛋白质。在这里，我们表明恶性疟原虫在内质网中表达 DPY19 色氨酸 C-甘露糖基转移酶，并且 DPY19 缺陷会消除 C-糖基化，使 TRAP 黏附素家族成员失稳，并抑制向蚊子的传播。使用晶格光片显微镜在四个维度上对整个疟原虫配子发生进行成像，揭示了 ΔDPY19 配子体逸出和出芽的缺陷。尽管逸出减少，但 ΔDPY19 小配子仍然可以使大配子受精，形成动合子，但这些在蚊子感染中被阻断。配子发生缺陷与 MTRAP 的不稳定性相对应，我们表明 MTRAP 在恶性疟原虫中被 C-甘露糖基化，而动合子缺陷与 ΔDPY19 背景下 CTRP 分泌缺陷一致。DPY19 的遗传互补恢复了动合子感染性、裂殖子产生和 C-甘露糖基化活性。因此，DPY19 的色氨酸 C-甘露糖基化确保了 TSR 蛋白质在两个生命周期阶段的质量控制，从而成功传播人类疟原虫。
