Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Plant Physiol. 1985 Apr;77(4):833-9. doi: 10.1104/pp.77.4.833.
In addition to leghemoglobin, at least nine nodule-specific polypeptides from the alfalfa (Medicago sativa L.)-Rhizobium meliloti symbiosis were identified by immune assay. Some of these polypeptides may be subunits of larger proteins but none appeared to be subunits of the same multimeric protein. All nine of the nodule-specific polypeptides were localized to within the plant cytosol; they were not found in extracts of bacteroids or in the peribacteroid space. At least one of these nodule-specific polypeptides was found to be antigenically related to nodule-specific polypeptides in pea and/or soybean. Ineffective nodules elicited by R. meliloti strains containing mutations in four different genes required for nitrogenase synthesis contained reduced concentrations of leghemoglobin and of several of the nodule-specific polypeptides. Other nodule-specific polypeptides were unaltered or actually enriched in the ineffective nodules. Many of the differences between the ineffective and effective nodules were apparent in nodules harvested shortly after the nodules became visible. These differences were greatly amplified in older nodules. When the four ineffective nodule types were compared to one another, there were clear quantitative differences in the concentrations of several of the nodule-specific polypeptides. These differences suggest that lack of a functional nitrogenase does not have a single direct effect on nodule development.
除了豆血红蛋白外，苜蓿（Medicago sativa L.）-根瘤菌共生体中至少有 9 种结瘤特异性多肽通过免疫测定法被鉴定出来。这些多肽中的一些可能是较大蛋白质的亚基，但没有一种似乎是同一多聚体蛋白质的亚基。所有 9 种结瘤特异性多肽都定位于植物细胞质内；它们未在类菌体提取物或类菌体周质空间中被发现。这些结瘤特异性多肽中的至少一种被发现与豌豆和/或大豆中的结瘤特异性多肽具有抗原相关性。由根瘤菌菌株引起的无效结节，这些菌株含有合成固氮酶所需的四个不同基因的突变，含有较低浓度的豆血红蛋白和几种结瘤特异性多肽。其他结瘤特异性多肽在无效结节中未改变或实际上富集。在无效和有效结节之间的许多差异在结节刚刚可见时就已经很明显了。这些差异在较老的结节中被大大放大。当将四种无效的结节类型相互比较时，几种结瘤特异性多肽的浓度存在明显的定量差异。这些差异表明，缺乏功能性固氮酶对结节发育没有单一的直接影响。
