Cloning, characterization, and immunolocalization of a mycorrhiza-inducible 1-deoxy-D-xylulose 5-phosphate reductoisomerase in arbuscule-containing cells of maize
Cloning, characterization, and immunolocalization of a mycorrhiza-inducible 1-deoxy-D-xylulose 5-phosphate reductoisomerase in arbuscule-containing cells of maize
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DOI：
10.1104/pp.103.032342
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发表时间：
2004-02-01
期刊：
影响因子：
7.4
通讯作者：
Walter, MH
中科院分区：
文献类型：
--
作者：
Hans, J;Hause, B;Walter, MH
共生丛枝菌根真菌在植物根部的定殖常常导致几种脱辅基类胡萝卜素的积累。相应的类胡萝卜素前体来源于质体2-C-甲基-D-β 4-磷酸途径。我们已经从玉米中克隆并鉴定了1-脱氧-D-木酮糖5-磷酸还原异构酶（DXR），该酶催化该途径的第一个关键步骤。通过在大肠杆菌中异源表达编码成熟蛋白的序列来完成功能鉴定。DXR在玉米根中在菌根化过程中上调，如在转录物和蛋白质水平所示，但在叶片和幼苗中也很丰富。检查测序的基因组和表达序列标签（EST）数据库主张单拷贝DXR基因。在菌根根使用亲和纯化的抗体的免疫定位研究揭示了DXR定位在质体周围的主要共生结构，丛枝。DXR蛋白积累与丛枝发育密切相关。DXR蛋白的最高水平在这些结构的成熟和初始衰老前后达到。我们进一步证明了一个含DXR的质体网络周围的丛枝，这是高度互连的成熟，功能状态的丛枝。我们的研究结果意味着在丛枝生命周期的脱辅基类胡萝卜素或其各自的类胡萝卜素前体的一个仍然未知的性质的功能作用。
Colonization of plant roots by symbiotic arbuscular mycorrhizal fungi frequently leads to the accumulation of several apocarotenoids. The corresponding carotenoid precursors originate from the plastidial 2-C-methyl-D-erythritol 4-phosphate pathway. We have cloned and characterized 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), catalyzing the first committed step of the pathway, from maize (Zea mays). Functional identification was accomplished by heterologous expression of sequences coding for the mature protein in Escherichia coli. DXR is up-regulated in maize roots during mycorrhization as shown at transcript and protein levels, but is also abundant in leaves and young seedlings. Inspection of sequenced genomes and expressed sequence tag (EST) databases argue for a single-copy DXR gene. Immunolocalization studies in mycorrhizal roots using affinity-purified antibodies revealed a DXR localization in plastids around the main symbiotic structures, the arbuscules. DXR protein accumulation is tightly correlated with arbuscule development. The highest level of DXR protein is reached around maturity and initial senescence of these structures. We further demonstrate the formation of a DXR-containing plastidial network around arbuscules, which is highly interconnected in the mature, functional state of the arbuscules. Our findings imply a functional role of a still unknown nature for the apocarotenoids or their respective carotenoid precursors in the arbuscular life cycle.