Department of Plant Pathology, University of California Davis, Davis, California, United States of America.
PLoS One. 2010 Feb 17;5(2):e9262. doi: 10.1371/journal.pone.0009262.
Recognition of pathogen-associated molecular patterns by pattern recognition receptors (PRRs) activates the innate immune response. Although PRR-mediated signaling events are critical to the survival of plants and animals, secretion and localization of PRRs have not yet been clearly elucidated. Here we report the in vivo interaction of the endoplasmic reticulum (ER) chaperone BiP3 with the rice XA21 PRR, which confers resistance to the Gram negative bacterium, Xanthomonas oryzae pv. oryzae (Xoo). We show that XA21 is glycosylated and is primarily localized to the ER and also to the plasma membrane (PM). In BiP3-overexpressing rice plants, XA21-mediated immunity is compromised, XA21 stability is significantly decreased, and XA21 proteolytic cleavage is inhibited. BiP3 overexpression does not affect the general rice defense response, cell death or brassinolide-induced responses. These results indicate that BiP3 regulates XA21 protein stability and processing and that this regulation is critical for resistance to Xoo.
模式识别受体（PRRs）识别病原体相关分子模式，从而激活先天免疫反应。尽管 PRR 介导的信号事件对植物和动物的生存至关重要，但 PRR 的分泌和定位尚未得到明确阐明。在这里，我们报告了内质网（ER）伴侣蛋白 BiP3 与水稻 XA21 PRR 的体内相互作用，该 PRR 赋予了对革兰氏阴性细菌，稻黄单胞菌 pv。oryzae（Xoo）的抗性。我们表明 XA21 被糖基化，主要定位于 ER，也定位于质膜（PM）。在 BiP3 过表达的水稻植物中，XA21 介导的免疫受到损害，XA21 的稳定性显著降低，XA21 的蛋白水解切割受到抑制。BiP3 的过表达并不影响水稻的一般防御反应、细胞死亡或油菜素内酯诱导的反应。这些结果表明 BiP3 调节 XA21 蛋白稳定性和加工，这种调节对 Xoo 的抗性至关重要。
