Virus-encoded toxin of Ustilago maydis: two polypeptides are essential for activity
Virus-encoded toxin of Ustilago maydis: two polypeptides are essential for activity
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玉米黑粉菌病毒编码毒素：两种多肽对于活性至关重要
DOI：
10.1128/mcb.7.1.470-477.1987
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发表时间：
1987
影响因子：
5.3
通讯作者：
J. Bruenn
中科院分区：
文献类型：
--
作者：
T. Peery;T. Shabat;R. Steinlauf;Y. Koltin;J. Bruenn
含有双链RNA病毒的玉米黑粉菌细胞分泌一种病毒编码的毒素，同一物种和相关物种的其他细胞对该毒素敏感。对影响KP6毒素表达的突变体进行了表征，所有突变体均为病毒突变体。对温度敏感的非杀伤突变体表明，该毒素由两个多肽组成，12.5K和10K，这是毒性活性所必需的。温度敏感的非杀伤突变体的10K多肽的表达受到影响，其毒性活性恢复的10K多肽添加到其分泌的失活毒素。这些结果导致了对已知在体外互补的其他突变体的重新检查。发现每一种都分泌两种多肽中的一种。在这里，我们首次表明，P6毒素由两个多肽，不相互作用的解决方案，但都是必不可少的毒性作用。对两种多肽之间相互作用的研究表明，多肽之间不存在共价键或氢键。毒素活性不受毒素制剂和培养基中存在的0.3 M NaCl的影响，表明这种相互作用中不涉及静电力。而且，两种多肽不共享共同的抗原决定簇。这两种多肽的活性似乎取决于与靶细胞的顺序相互作用，并且是10 K多肽启动了毒性作用。美国的相似性。玉米瘟病毒编码的毒素对酿酒酵母毒素的影响进行了讨论。
Cells of Ustilago maydis containing double-stranded RNA viruses secrete a virus-encoded toxin to which other cells of the same species and related species are sensitive. Mutants affected in the expression of the KP6 toxin were characterized, and all were viral mutants. A temperature-sensitive nonkiller mutant indicated that the toxin consists of two polypeptides, 12.5K and 10K, that are essential for the toxic activity. The temperature-sensitive nonkiller mutant was affected in the expression of the 10K polypeptide, and its toxic activity was restored by the addition of the 10K polypeptide to its secreted inactive toxin. These results led to the reexamination of other mutants that were known to complement in vitro. Each was found to secrete one of the two polypeptides. Here we show for the first time that P6 toxin consists of two polypeptides that do not interact in solution, but both are essential for the toxic effect. Studies on the interaction between the two polypeptides indicated that there are no covalent or hydrogen bonds between the polypeptides. Toxin activity is not affected by the presence of 0.3 M NaCl in the toxin preparations and in the medium, suggesting that no electrostatic forces are involved in this interaction. Also, the two polypeptides do not share common antigenic determinants. The activity of the two polypeptides appears to be dependent on a sequential interaction with the target cell, and it is the 10K polypeptide that initiates the toxic effect. The similarity of the U. maydis virus-encoded toxin to that of Saccharomyces cerevisiae is discussed.