Oxygen regulation of a nodule-located carbonic anhydrase in alfalfa
Oxygen regulation of a nodule-located carbonic anhydrase in alfalfa
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DOI：
10.1104/pp.124.3.1059
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发表时间：
2000-11-01
期刊：
影响因子：
7.4
通讯作者：
Crespi, M
中科院分区：
文献类型：
--
作者：
Gálvez, S;Hirsch, AM;Crespi, M
对氧气渗透性的控制是豆科植物根瘤共生固氮功能的关键。内皮层（IC）似乎是这种调节的主要部位。在苜蓿（紫花苜蓿）结节，Msca1基因编码的碳酸酐酶（CA）的表达被发现以前被限制到IC。我们现在已经提出了针对重组Msca1蛋白的抗体，并使用它们，连同针对马铃薯叶CA提出的抗体，以证明成熟结节中存在两种形式的CA。每种抗体识别结节组织中不同的CA同种型。免疫定位显示，叶相关的CA主要定位在固氮区，而Msca1蛋白仅限于IC区域，在不确定和确定的结节。在苜蓿根瘤生长在不同的O-2浓度，观察到外部氧压力和Msca1蛋白质含量之间的负相关性在IC，推定的扩散屏障的网站。因此，Msca1是发生在结节中参与气体交换的IC细胞中的生理过程的分子靶标。
Control of the permeability to oxygen is critical for the function of symbiotic nitrogen fixation in legume nodules. The inner cortex (IC) seems to be a primary site for this regulation. In alfalfa (Medicago sativa) nodules, expression of the Msca1 gene encoding a carbonic anhydrase (CA) was previously found to be restricted to the IC. We have now raised antibodies against recombinant Msca1 protein and used them, together with antibodies raised against potato leaf CA, to demonstrate the presence of two forms of CA in mature nodules. Each antibody recognizes a different CA isoform in nodule tissues. Immunolocalization revealed that leaf-related CAs were localized primarily in the nitrogen-fixing zone, whereas the Msca1 protein was restricted exclusively to the IC region, in indeterminate and determinate nodules. In alfalfa nodules grown at various O-2 concentrations, an inverse correlation was observed between the external oxygen pressure and Msca1 protein content in the IC, the site of the putative diffusion barrier. Thus Msca1 is a molecular target of physiological processes occurring: in the IC cells involved in gas exchange in the nodule.