Bernat-Silvestre Cesar, Ma Yingxuan, Johnson Kim, Ferrando Alejandro, Aniento Fernando, Marcote María Jesús
Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, Valencia, Spain.
School of BioSciences, The University of Melbourne, Parkville, VIC, Australia.
Front Plant Sci. 2022 Feb 11;13:817915. doi: 10.3389/fpls.2022.817915. eCollection 2022.
Lipid remodeling of Glycosylphosphatidylinositol (GPI) anchors is required for their maturation and may influence the localization and function of GPI-anchored proteins (GPI-APs). Maturation of GPI-anchors is well characterized in animals and fungi but very little is known about this process in plants. In yeast, the GPI-lipid remodeling occurs entirely at the ER and is initiated by the remodeling enzyme Bst1p (Post-Glycosylphosphatidylinositol Attachment to Proteins inositol deacylase 1 -PGAP1- in mammals and ). Next, the remodeling enzyme Per1p (Post-Glycosylphosphatidylinositol Attachment to Proteins phospholipase 3 -PGAP3- in mammals) removes a short, unsaturated fatty acid of phosphatidylinositol (PI) that is replaced with a very long-chain saturated fatty acid or ceramide to complete lipid remodeling. In mammals, lipid remodeling starts at the ER and is completed at the Golgi apparatus. Studies of the gene showed that the lipid remodeling of the GPI anchor is critical for the final localization of GPI-APs. Here we characterized loss-of-function mutants of / like genes ( and ). Our results suggest that function is required for the efficient transport of GPI-anchored proteins from the ER to the plasma membrane/cell wall. In addition, loss of function of increases susceptibility to salt and osmotic stresses that may be due to the altered localization of GPI-APs in this mutant. Furthermore, complements a yeast strain lacking gene suggesting that PGAP3B and Per1p are functional orthologs. Finally, subcellular localization studies suggest that PGAP3A and PGAP3B cycle between the ER and the Golgi apparatus.
糖基磷脂酰肌醇（GPI）锚定物的脂质重塑是其成熟所必需的，并且可能影响GPI锚定蛋白（GPI-APs）的定位和功能。GPI锚定物的成熟在动物和真菌中已有充分研究，但在植物中对此过程知之甚少。在酵母中，GPI脂质重塑完全发生在内质网（ER），并由重塑酶Bst1p（哺乳动物中的糖基磷脂酰肌醇附着蛋白肌醇脱酰酶1 -PGAP1-）启动。接下来，重塑酶Per1p（哺乳动物中的糖基磷脂酰肌醇附着蛋白磷脂酶3 -PGAP3-）去除磷脂酰肌醇（PI）的一个短的不饱和脂肪酸，并用一个非常长链的饱和脂肪酸或神经酰胺取代，以完成脂质重塑。在哺乳动物中，脂质重塑始于内质网并在高尔基体完成。对 基因的研究表明，GPI锚定物的脂质重塑对于GPI-APs的最终定位至关重要。在这里，我们对 / 样基因（ 和 ）的功能缺失突变体进行了表征。我们的结果表明， 功能对于GPI锚定蛋白从内质网到质膜/细胞壁的有效转运是必需的。此外， 功能的丧失增加了对盐和渗透胁迫的敏感性，这可能是由于该突变体中GPI-APs的定位改变所致。此外， 补充了缺乏 基因的酵母菌株，表明PGAP3B和Per1p是功能直系同源物。最后，亚细胞定位研究表明，PGAP3A和PGAP3B在内质网和高尔基体之间循环。
