Glycosylphosphatidylinositol-anchored proteins are required for cell wall synthesis and morphogenesis in Arabidopsis
Glycosylphosphatidylinositol-anchored proteins are required for cell wall synthesis and morphogenesis in Arabidopsis
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DOI：
10.1105/tpc.105.031815
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发表时间：
2005-04-01
期刊：
影响因子：
11.6
通讯作者：
Somerville, C
中科院分区：
文献类型：
--
作者：
Gillmor, CS;Lukowitz, W;Somerville, C
在径向肿胀胚胎突变体的遗传筛选中，鉴定出了五个名为 PEANUT1-5 (PNT) 的基因座的突变。 pnt1 细胞壁显示结晶纤维素减少，果胶增加，以及果胶、木葡聚糖和胼胝质的不规则和异位沉积。此外，pnt1花粉的活力低于野生型，pnt1胚胎的形态发生延迟，并在芽和根分生组织中表现出缺陷。 PNT1 基因编码哺乳动物 PIG-M 的拟南芥同源物，PIG-M 是合成糖基磷脂酰肌醇 (GPI) 锚所需的内质网定位甘露糖基转移酶。所有五个 pnt 突变体均表现出 GPI 锚定蛋白积累的强烈减少，表明它们在 GPI 锚定合成方面都存在缺陷。尽管突变体对幼苗具有致死性，但 pnt1 细胞能够作为未分化愈伤组织在有限时间内增殖，并且不会出现 pnt1 胚胎中所见的异位细胞壁物质的大量沉积。胚胎和愈伤组织中 pnt1 细胞的不同表型表明这两种组织中细胞壁合成对 GPI 锚定蛋白的不同需求，并指出 GPI 锚定在协调多细胞生长中的重要性。
Mutations at five loci named PEANUT1-5 (PNT) were identified in a genetic screen for radially swollen embryo mutants. pnt1 cell walls showed decreased crystalline cellulose, increased pectins, and irregular and ectopic deposition of pectins, xyloglucans, and callose. Furthermore, pnt1 pollen is less viable than the wild type, and pnt1 embryos were delayed in morphogenesis and showed defects in shoot and root meristems. The PNT1 gene encodes the Arabidopsis thaliana homolog of mammalian PIG-M, an endoplasmic reticulum-localized mannosyltransferase that is required for synthesis of the glycosylphosphatidylinositol (GPI) anchor. All five pnt mutants showed strongly reduced accumulation of GPI-anchored proteins, suggesting that they all have defects in GPI anchor synthesis. Although the mutants are seedling lethal, pnt1 cells are able to proliferate for a limited time as undifferentiated callus and do not show the massive deposition of ectopic cell wall material seen in pnt1 embryos. The different phenotype of pnt1 cells in embryos and callus suggest a differential requirement for GPI-anchored proteins in cell wall synthesis in these two tissues and points to the importance of GPI anchoring in coordinated multicellular growth.