Carbohydrate binding activities of Bradyrhizobium japonicum: IV. Effect of lactose and flavones on the expression of the lectin, BJ38.
Carbohydrate binding activities of Bradyrhizobium japonicum: IV. Effect of lactose and flavones on the expression of the lectin, BJ38.
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日本慢生根瘤菌的碳水化合物结合活性：IV。
DOI：
10.1007/bf00731210
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发表时间：
1994
影响因子：
3
通讯作者：
Schindler,M
中科院分区：
文献类型：
--
作者：
Loh,JT;Ho,SC;Wang,JL;Schindler,M
BJ 38是一种半乳糖/乳糖特异性凝集素，分子量约为38000。它参与介导细菌对大豆根部的粘附，导致固氮共生的建立。当在收获用于BJ 38分离的细胞之前将配体乳糖添加到细菌培养物中至少1小时时，发现蛋白质的产率以剂量依赖性方式升高。在0.50 μm处观察到半数最大刺激;在0.11 μ m处效果饱和，其中获得10倍更高的BJ 38产量。当在1 mM的浓度下比较时，与乳糖相比对BJ 38具有较低亲和力的糖苷产生相应较小的诱导作用。乳糖诱导的更高水平的BJ 38还表现为在细胞表面可检测到的BJ 38的量的升高和更高数量的B. japonicum细胞吸附到大豆细胞上。令人惊讶的是，用乳糖观察到的BJ 38表达的诱导也用某些但不是全部的类黄酮诱导细菌的nodgenes观察到;染料木黄酮模仿用乳糖观察到的诱导，而毛地黄黄酮未能刺激BJ 38的产生。
BJ38 is a galactose/lactose-specific lectin (Mr∼ 38000) found at one pole ofBradyrhizobium japonicum. It has been implicated in mediating the adhesion of the bacteria to soybean roots, leading to the establishment of a nitrogen-fixing symbiosis. When the ligand lactose is added to cultures of the bacteria for at least 1 h prior to harvesting the cells for BJ38 isolation, the yield of the protein was found to be elevated in a dose-dependent fashion. Half maximal stimulation was observed at ∼ 50 µm; the effect was saturated at ∼ 1mm, where a 10-fold higher yield of BJ38 was obtained. Saccharides with a lower affinity for BJ38 than lactose yielded a correspondingly smaller induction effect when compared at a concentration of 1mm. The higher level of BJ38 induced by lactose is also manifested by an elevated amount of BJ38 detectable at the cell surface and by a higher number ofB. japonicumcells adsorbed onto soybean cells. Surprisingly, the induction of BJ38 expression seen with lactose was also observed with certain, but not all, flavonoids that induce thenodgenes of the bacteria; genistein mimicked the induction observed with lactose, whereas luteolin failed to stimulate BJ38 production.