• Golgi is a critical compartment for both the reutilisation of the essential micronutrient manganese (Mn) and its detoxification. However, whether Mn plays a role in the Golgi remains to be demonstrated in plants.
• We characterised the function of PML3, a member of the Unknown Protein Family UPF0016, in Mn transport and the regulation of plant growth, Golgi glycosylation and cell wall biosynthesis in Arabidopsis. We also investigated the relationship of PML3 with NRAMP2, a trans-Golgi network localised Mn transporter.
• PML3-GFP is preferentially localised in the cis-Golgi. PML3 can transport Mn to rescue the hypersensitivity of yeast mutant Δpmr1 to excess Mn. Two mutant alleles of PML3 displayed reduced plant growth and impaired seed development under Mn-deficient conditions. The pml3 mutants also showed impaired Golgi glycosylation and cell wall biosynthesis under Mn deficiency. Double mutations of PML3 and NRAMP2 showed improved plant growth compared with that of single mutants under Mn deficiency, implying that PML3 and NRAMP2 play opposite roles in the regulation of Golgi Mn levels.
• Our results suggest that PML3 mediates Mn uptake into the Golgi compartments, which is required for proper protein glycosylation and cell wall biosynthesis under Mn-deficient conditions.

中文翻译：

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高尔基体锰转运蛋白 PML3 通过调节高尔基体糖基化和细胞壁生物合成来调节拟南芥的生长

• 高尔基体是重新利用必需微量营养素锰 (Mn) 及其解毒的关键隔间。然而，锰是否在高尔基体中发挥作用仍有待植物中的证实。
• 我们描述了 PML3（未知蛋白质家族 UPF0016 的成员）在拟南芥中锰转运和植物生长调节、高尔基糖基化和细胞壁生物合成中的功能。我们还研究了 PML3 与 NRAMP2 的关系，NRAMP2 是一种跨高尔基网络定位的锰转运蛋白。
• PML3-GFP 优先定位于顺式高尔基体。PML3 可以运输 Mn 以挽救酵母突变体 Δ pmr1对过量 Mn 的超敏反应。PML3的两个突变等位基因在缺锰条件下表现出植物生长减少和种子发育受损。pml3突变体在锰缺乏的情况下也表现出受损的高尔基糖基化和细胞壁生物合成。与单突变体相比， PML3和NRAMP2的双突变在缺锰条件下表现出改善的植物生长，这意味着PML3和NRAMP2在调节高尔基体锰水平中起相反的作用。
• 我们的研究结果表明，PML3 介导高尔基体吸收 Mn，这是在 Mn 缺乏条件下适当的蛋白质糖基化和细胞壁生物合成所必需的。