Department of Plant Science, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
PLoS One. 2012;7(9):e44493. doi: 10.1371/journal.pone.0044493. Epub 2012 Sep 6.
Protein disulfide isomerase (PDI) is a chaperone protein involved in oxidative protein folding by acting as a catalyst and assisting folding in the endoplasmic reticulum (ER). A genome database search showed that rice contains 19 PDI-like genes. However, their functions are not clearly identified. This paper shows possible functions of rice PDI-like protein 1-1 (PDIL1-1) during seed development. Seeds of the T-DNA insertion PDIL1-1 mutant, PDIL1-1Δ, identified by genomic DNA PCR and western blot analysis, display a chalky phenotype and a thick aleurone layer. Protein content per seed was significantly lower and free sugar content higher in PDIL1-1Δ mutant seeds than in the wild type. Proteomic analysis of PDIL1-1Δ mutant seeds showed that PDIL1-1 is post-translationally regulated, and its loss causes accumulation of many types of seed proteins including glucose/starch metabolism- and ROS (reactive oxygen species) scavenging-related proteins. In addition, PDIL1-1 strongly interacts with the cysteine protease OsCP1. Our data indicate that the opaque phenotype of PDIL1-1Δ mutant seeds results from production of irregular starch granules and protein body through loss of regulatory activity for various proteins involved in the synthesis of seed components.
蛋白质二硫键异构酶（PDI）是一种伴侣蛋白，通过充当催化剂和协助内质网（ER）中的折叠，参与氧化蛋白折叠。基因组数据库搜索表明，水稻含有 19 种 PDI 样基因。然而，它们的功能尚不清楚。本文展示了水稻 PDI 样蛋白 1-1（PDIL1-1）在种子发育过程中的可能功能。通过基因组 DNA PCR 和 Western blot 分析鉴定的 T-DNA 插入 PDIL1-1 突变体（PDIL1-1Δ）种子表现出垩白表型和厚糊粉层。PDIL1-1Δ突变体种子的每粒种子的蛋白质含量明显低于野生型，游离糖含量高于野生型。PDIL1-1Δ突变体种子的蛋白质组学分析表明，PDIL1-1 是翻译后调控的，其缺失导致包括葡萄糖/淀粉代谢和 ROS（活性氧）清除相关蛋白在内的多种种子蛋白的积累。此外，PDIL1-1 与半胱氨酸蛋白酶 OsCP1 强烈相互作用。我们的数据表明，PDIL1-1Δ 突变体种子的不透明表型是由于参与种子成分合成的各种蛋白质的调节活性丧失而导致不规则淀粉粒和蛋白体的产生。
