Activation of an ER-body-localized β-glucosidase via a cytosolic binding partner in damaged tissues of Arabidopsis thaliana
Activation of an ER-body-localized β-glucosidase via a cytosolic binding partner in damaged tissues of Arabidopsis thaliana
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DOI：
10.1093/pcp/pci126
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发表时间：
2005-07-01
影响因子：
4.9
通讯作者：
Hara-Nishimura, I
中科院分区：
文献类型：
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作者：
Nagano, AJ;Matsushima, R;Hara-Nishimura, I
ER 体是内质网 (ER) 衍生的细胞器。由于 ER 体是由莲座叶中的损伤和茉莉酸甲酯 (MeJA) 处理诱导产生的，因此它们可能负责防御系统。最近，我们分离出没有 ER 体的指甲突变体，并发现指甲突变体中 PYK10 和 PBP1（PYK10 结合蛋白 1：At3g16420）的水平降低。 PYK10 是一种位于 ER 体内的 β-葡萄糖苷酶。 PBP1 由两个重复区域组成，每个区域都与 Jacalin（一种木香的碳水化合物结合蛋白（凝集素））的 a 链高度同源。我们在这项研究中表明 PYK10 有两种形式，活性形式和非活性形式。在根匀浆的培养过程中，活性形式的量增加。另一方面，PYK10 分为可溶性和不溶性形式。活性PYK10分子主要以不溶性形式存在，非活性PYK10分子保持可溶性。这表明PYK10的活化需要聚合。在 pbp1 突变体和野生型的匀浆中，PYK10 变得不溶，而 pbp1 中的 PYK10 活性仅为野生型的一半。 PBP1 具有与 PYK10 相互作用的能力。尽管如此，PBP1 不结合活性 PYK10。这些结果表明PBP1对PYK10的激活有一定影响。此外，PBP1被发现具有与PYK10不同的亚细胞分布。当害虫组织受损和亚细胞结构被破坏时，PBP1 可能像分子伴侣一样促进 PYK10 的正确聚合。
The ER body is an endoplasmic reticulum (ER)derived organelle. Because ER bodies are induced by wounding and methyl jasmonate (MeJA) treatment in rosette leaves, they might be responsible for defense systems. Recently, we isolated nail mutants that have no ER body and showed that the levels of PYK10 and PBP1 (PYK10-binding protein 1: At3g16420) were decreased in nail mutants. PYK10 is a beta-glucosidase that is localized in ER bodies. PBP1 consists of two repeated regions, each of which is highly homologous to the a-chain of jacalin, a carbohydrate-binding protein (lectin) of Artocarpus integriforia. We show in this study that PYK10 has two forms, an active form and an inactive form. The amount of active form increased during incubation of root homogenate. On the other hand, PYK10 separated into soluble and insoluble forms. Active PYK10 molecules mainly occurred as the insoluble form and inactive PYK10 molecules remain soluble. This suggests that the activation of PYK10 needs polymerization. In homogenates of both a pbp1 mutant and the wild type, PYK10 becomes insoluble, while PYK10 activity in pbp1 is only half of that in the wild type. PBP1 has an ability to interact with PYK10. Nonetheless, PBP1 does not bind active PYK10. These results suggest that PBP1 has some effect on the activation of PYK10. In addition, PBP1 was found to have a different subcellular distribution from PYK10. PBP1 may act like a molecular chaperone that facilitates the correct polymerization of PYK10, when tissues are damaged and subcellular structures are destroyed by pests.