Max-Planck-Institut für Züchtungsforschung, Abteilung Schell, D-5000 Köln 30, FRG.
EMBO J. 1988 Mar;7(3):583-8. doi: 10.1002/j.1460-2075.1988.tb02850.x.
The 46.8-kd NodC protein of Rhizobium meliloti is a membrane protein, essential for nodule formation. Gene fusions of nodC to a portion of the lambda cI repressor gene were used to define the membrane-anchor domain which is necessary for membrane insertion of the NodC protein into the membrane. The transmembrane orientation of NodC was confirmed by surface-specific radiolabeling and proteolysis experiments. A highly hydrophobic transmembrane-anchor domain was found near the carboxyl terminus, separating a large extracellular domain which contains an unusual cysteine-rich cluster from a short putative intracellular domain. Cross-linking studies showed that the NodC protein exists in the membrane probably as a dimer. The domain structure of the NodC protein shows striking similiarities with cell surface receptors. In nodules of various legumes a truncated form of the NodC protein was detected. The processed NodC was associated with the bacteroids and the amount of this protein increased during nodule development.
苜蓿中华根瘤菌 46.8kDa 的 NodC 蛋白是一种膜蛋白，对根瘤的形成是必需的。将 nodC 基因与 λ cI 阻遏蛋白的一部分融合，用于定义膜锚定域，该域对于 NodC 蛋白插入膜中是必需的。通过表面特异性放射性标记和蛋白水解实验证实了 NodC 的跨膜取向。在羧基末端附近发现了一个高度疏水性的跨膜锚定域，将一个包含不寻常的富含半胱氨酸簇的大细胞外域与一个短的假定细胞内域分隔开。交联研究表明，NodC 蛋白可能以二聚体的形式存在于膜中。NodC 蛋白的结构域显示出与细胞表面受体惊人的相似性。在各种豆科植物的根瘤中，检测到一种截短形式的 NodC 蛋白。加工后的 NodC 与类菌体相关联，并且这种蛋白的量在根瘤发育过程中增加。
