A novel ER-derived compartment, the ER body, selectively accumulates a β-glucosidase with an ER-retention signal in Arabidopsis
A novel ER-derived compartment, the ER body, selectively accumulates a β-glucosidase with an ER-retention signal in Arabidopsis
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DOI：
10.1046/j.1365-313x.2003.01636.x
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发表时间：
2003-02-01
期刊：
影响因子：
7.2
通讯作者：
Hara-Nishimura, I
中科院分区：
文献类型：
--
作者：
Matsushima, R;Kondo, M;Hara-Nishimura, I
内质网体是拟南芥内质网中的一个新结构。与ER体广泛分布的整株幼苗相反，莲座叶没有ER体。最近，我们报道了创伤胁迫诱导莲座叶中许多ER体的形成，表明ER体在植物的防御系统中起作用。在表达具有ER滞留信号HDEL的绿色荧光蛋白（GFP）的转基因植物（GFP-h）中观察到ER体。将这些浓缩在1000-g GFP-h植物的沉淀（P1）中。我们分离到一个拟南芥突变体，nai 1，其中荧光ER体几乎没有检测到整个植物。我们发现，一个65 kDa的蛋白质是专门积累在P1部分的GFP-h植物，但不是在P1部分的nai 1植物。N-末端肽测序显示，65-kDa的蛋白质是β-葡糖苷酶，PYK 10，具有ER-保留信号，KDEL。免疫细胞化学显示PYK 10定位于ER小体。与GFP-HDEL的积累相比，PYK 10的积累对ER体更具特异性，GFP-HDEL的积累与池状ER和ER体都相关。PYK 10是拟南芥幼苗子叶、下胚轴和根中的主要蛋白质之一，而PYK 10在没有ER体的莲座叶中未检测到。这些结果表明PYK 10是ER体的主要成分。PYK 10可能在植物受到昆虫或创伤时产生防御化合物。
The ER body is a novel compartment that is derived from endoplasmic reticulum (ER) in Arabidopsis . In contrast to whole seedlings which have a wide distribution of the ER bodies, rosette leaves have no ER bodies. Recently, we reported that wound stress induces the formation of many ER bodies in rosette leaves, suggesting that the ER body plays a role in the defense system of plants. ER bodies were visualized in transgenic plants (GFP-h) expressing green fluorescent protein (GFP) with an ER-retention signal, HDEL. These were concentrated in a 1000-g pellet (P1) of GFP-h plants. We isolated an Arabidopsis mutant, nai1, in which fluorescent ER bodies were hardly detected in whole plants. We found that a 65-kDa protein was specifically accumulated in the P1 fraction of GFP-h plants, but not in the P1 fraction of nai1 plants. N-terminal peptide sequencing revealed that the 65-kDa protein was a beta-glucosidase, PYK10, with an ER-retention signal, KDEL. Immunocytochemistry showed that PYK10 was localized in the ER bodies. Compared with the accumulation of GFP-HDEL, which was associated with both cisternal ER and ER bodies, the accumulation of PYK10 was much more specific to ER bodies. PYK10 was one of the major proteins in cotyledons, hypocotyls and roots of Arabidopsis seedlings, while PYK10 was not detected in rosette leaves that have no ER bodies. These findings indicated that PYK10 is the main component of ER bodies. It is possible that PYK10 produces defense compounds when plants are damaged by insects or wounding.