Carbohydrate binding activities of Bradyrhizobium japonicum. III. Lectin expression, bacterial binding, and nodulation efficiency.
Carbohydrate binding activities of Bradyrhizobium japonicum. III. Lectin expression, bacterial binding, and nodulation efficiency.
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日本慢生根瘤菌的碳水化合物结合活性。
DOI：
10.1046/j.1365-313x.1994.5060873.x
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Loh,JT
中科院分区：
文献类型：
--
作者：
Ho,SC;Wang,JL;Schindler,M;Loh,JT
在以前的研究中，有证据表明，命名为BJ 38的慢生型大豆根瘤菌凝集素介导了所观察到的细菌的碳水化合物特异性结合活性，包括对大豆根细胞的糖特异性粘附。在本研究中，它被发现，bothB.日本大豆根瘤菌的BJ38以及纯化的BJ38主要结合大豆根的幼根出生根毛，并且在小得多的程度上结合根冠、成熟根毛、上胚轴或下胚轴区域。因此，细菌和分离的凝集素优先结合的区域与大豆根最容易受到B的区域一致。日本血吸虫感染通过比较结合缺陷型突变体N4和N6与野生型的结合效率，研究了细菌结合对于结合过程的重要性。这些突变体已被证明在碳水化合物识别方面有缺陷，表现为它们与大豆根结合的能力减弱。将BJ38免疫定位于野生型B的细胞表面的一极。japonicum，但没有表面标记可以检测到的任何突变体。此外，相对于野生型，N4和N6都显示出抑制活性的显著降低。这些结果为B.在感染过程的初始阶段，最可能由BJ 38介导的日本血吸虫感染可能起重要作用。
In previous studies, evidence that theBradyrhizobium japonicumlectin, designated BJ38, mediated the observed carbohydrate‐specific binding activities of the bacteria, including the saccharide‐specific adhesion to soybean root cells was presented. In the present study, it is found that bothB. japonicum, as well as the purified BJ38, bind predominantly to young emergent root hairs of soybean roots and, to a much lesser extent, to the root cap, mature root hairs, epicotyl or hypocotyl regions. Thus, the region of preferential binding for both the bacteria and the isolated lectin coincide with the region of the soybean root most susceptible toB. japonicuminfection. The importance of bacterial binding for the nodulation process was studied by comparing the nodulation efficiency of binding‐deficient mutants N4 and N6 to the wild‐type. These mutants had been shown to be defective in carbohydrate recognition, as represented by their diminished ability to bind to soybean roots. BJ38 was immunolocalized to one pole of the cell surface of wild‐typeB. japonicum, but no surface labeling could be detected on either mutant. Moreover, both N4 and N6 showed a substantial decrease in nodulation activity, relative to the wild‐type. These results provide additional evidence that the carbohydrate binding activity ofB. japonicum, most probably mediated by BJ38, may play an important role(s) in the initial phases of the infection process.