Rhizobitoxine inhibition of hydrogenase synthesis in free-living Bradyrhizobium japonicum
Rhizobitoxine inhibition of hydrogenase synthesis in free-living Bradyrhizobium japonicum
复制标题
根瘤菌素抑制自由生活的日本慢生根瘤菌氢化酶合成
作者：
K. Minamisawa;K. Fukai;T. Asami
根瘤毒素产生的慢生根瘤菌种强烈阻止脱氢酶的表达在自由生活的慢生根瘤菌的解阻遏，虽然毒素已经合成的氢化酶蛋白的细胞的活性没有影响。二氢根瘤菌毒素，根瘤菌毒素的结构类似物，被证明是一个较弱的抑制剂的氢化酶去阻遏。在足以消除氢化酶表达的浓度下，根瘤菌毒素不会引起细胞死亡。氢化酶的大亚基在根瘤毒素存在下去阻遏后用抗体检测不到。从14 C-标记的氨基酸在去阻遏过程中合成的蛋白质的一般模式没有显着不同的存在或不存在的根瘤菌毒素。这些结果表明，根瘤菌毒素抑制自由生活的B的氢酶合成。山茱萸硫胱苷肽和蛋氨酸强烈阻止氢化酶去阻遏抑制根瘤菌毒素，这表明抑制涉及的含硫氨基酸在细胞中的水平。
Rhizobitoxine produced by Bradyrhizobium species strongly prevented derepression of hydrogenase expression in free-living Bradyrhizobium japonicum, although the toxin had no effect on the activity of cells which had already synthesized hydrogenase protein. Dihydrorhizobitoxine, a structural analog of rhizobitoxine, proved to be a less potent inhibitor of hydrogenase derepression. Rhizobitoxine did not cause cell death at a concentration sufficient to eliminate hydrogenase expression. The large subunit of hydrogenase was not detectable with antibody after derepression in the presence of rhizobitoxine. The general pattern of proteins synthesized from 14C-labeled amino acids during derepression was not significantly different in the presence or absence of rhizobitoxine. These results indicated that rhizobitoxine inhibited hydrogenase synthesis in free-living B. japonicum. Cystathionine and methionine strongly prevented the inhibition of hydrogenase derepression by rhizobitoxine, suggesting that the inhibition involves the level of sulfur-containing amino acids in the cell.