Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma, Nara, 630-0101 Japan.
Plant Cell Physiol. 2011 Feb;52(2):413-20. doi: 10.1093/pcp/pcq205. Epub 2011 Jan 6.
Plant class III peroxidase (PRX) catalyzes the oxidation and oxidative polymerization of a variety of phenolic compounds while reducing hydrogen peroxide. PRX proteins are classified into apoplast type and vacuole type based on the absence or the presence of C-terminal propeptides, which probably function as vacuolar sorting signals (VSSs). In this study, in order to improve our understanding of vacuole-type PRX, we analyzed regulatory mechanisms of vacuolar sorting of a model vacuole-type PRX, the C1a isozyme of horseradish (Armoracia rusticana) (HRP C1a). Using cultured transgenic tobacco cells and protoplasts derived from horseradish leaves, we characterized HRP C1a's VSS, which is a 15 amino acid C-terminal propeptide (C15). We found that the C-terminal hexapeptide of C15 (C6), which is well conserved among vacuole-type PRX proteins, forms the core of the C-terminal-dependent VSS. We also found that the function of C6 is enhanced by the remaining N-terminal part of C15 which probably folds into an amphiphilic α-helix.
植物 III 类过氧化物酶 (PRX) 催化各种酚类化合物的氧化和氧化聚合，同时还原过氧化氢。PRX 蛋白根据 C 末端前肽的缺失或存在分为质外体型和液泡型，该前肽可能作为液泡分选信号 (VSS) 发挥作用。在这项研究中，为了更好地理解液泡型 PRX，我们分析了模式液泡型 PRX，即辣根 (Armoracia rusticana) 的 C1a 同工酶 (HRP C1a) 的液泡分选的调控机制。使用培养的转基因烟草细胞和辣根叶片原生质体，我们对 HRP C1a 的 VSS 进行了表征，VSS 是一个 15 个氨基酸的 C 末端前肽 (C15)。我们发现 C15 的 C 末端六肽 (C6) 是液泡型 PRX 蛋白之间高度保守的核心，形成了 C 末端依赖性 VSS 的核心。我们还发现 C6 的功能由 C15 的剩余 N 末端部分增强，该部分可能折叠成两亲性 α-螺旋。
