Legocki R P, Verma D P
Cell. 1980 May;20(1):153-63. doi: 10.1016/0092-8674(80)90243-3.
Infection of legume roots with Rhizobium species results in the development of a root nodule structure in which the bacteria form an intracellular symbiosis with the plant. We report here that the infection of soybean (Glycine max L.) roots with Rhizobium japonicum results in the synthesis by the plant of at least 18-20 polypeptides other than leghemoglobin during the development of root nodules. Identification of these "nodule-specific" host polypeptides (referred to as nodulins) was accomplished by two-dimensional gel analysis of the immunoprecipitates formed by a "nodule-specific" antiserum with in vitro translation products of root-nodule polysomes that are free of bacteroidal contaminations. Nodulins account for 7-11% of the total 35S-methionine-labeled protein synthesized in the host cell cytoplasm, and the majority of them are of 12,000-20,000 molecular weight. These proteins are absent from the uninfected roots, bacteroids and free-living Rhizobium, and appear to be coded for the plant genes that may be obligatory for the development of symbiosis in the legume root nodules. Analysis of nodulins in ineffective (unable to fix nitrogen) nodules developed due to Rhizobium strains SM5 and 61A24 showed that their synthesis is reduced and their expression differentially influenced by mutations in rhizobia. Two polypeptides of bacterial origin were also found to be cross-reactive with the "nodule-specific" antiserum, suggesting that they are secreted by Rhizobium into the host cell cytoplasm during symbiotic nitrogen fixation.
豆科植物根被根瘤菌属感染会导致根瘤结构的形成，在这种结构中细菌与植物形成细胞内共生关系。我们在此报告，大豆（Glycine max L.）根被日本根瘤菌感染后，在根瘤发育过程中植物会合成至少18 - 20种除豆血红蛋白之外的多肽。通过对“根瘤特异性”抗血清与无类菌体污染的根瘤多核糖体体外翻译产物形成的免疫沉淀物进行二维凝胶分析，完成了对这些“根瘤特异性”宿主多肽（称为根瘤蛋白）的鉴定。根瘤蛋白占宿主细胞质中合成的总35S - 甲硫氨酸标记蛋白的7 - 11%，其中大多数分子量为12,000 - 20,000。这些蛋白质在未感染的根、类菌体和自由生活的根瘤菌中不存在，似乎是由植物基因编码的，这些基因可能是豆科植物根瘤共生发育所必需的。对由根瘤菌菌株SM5和61A24形成的无效（不能固氮）根瘤中的根瘤蛋白分析表明，它们的合成减少，并且其表达受根瘤菌突变的不同影响。还发现两种细菌来源的多肽与“根瘤特异性”抗血清有交叉反应，这表明它们在共生固氮过程中由根瘤菌分泌到宿主细胞质中。
