胰蛋白酶作用所揭示的大肠杆菌素K的作用阶段。
Stages in colicin K action, as revealed by the action of trypsin.
作者信息
Plate C A, Luria S E
出版信息
Proc Natl Acad Sci U S A. 1972 Aug;69(8):2030-4. doi: 10.1073/pnas.69.8.2030.
The effects of trypsin on Escherichia coli cells that have been treated with colicins have been examined. By the use of trypsin, it has been possible to demonstrate that the action of several colicins (E1, E2, and K) proceeds through at least two stages. Stage I is a period after colicin adsorption when trypsin can restore colony-forming ability to a colicin-treated cell. Stage I is followed by a period when trypsin is unable to restore colony-forming ability (stage II). The transition between stage I and stage II follows first-order kinetics, with a rate proportional to the number of killing units of colicin adsorbed.A quantitative comparison of the effects of colicin K on colony-forming ability and on several cellular processes indicates that colicin damage to these processes occurs in the stage II period of colicin action and is not subject to reversal by the trypsin treatment that restores viability to cell in stage I. The implications of these findings for an understanding of the mode of action of colicins are discussed.
已经研究了胰蛋白酶对经大肠杆菌素处理的大肠杆菌细胞的影响。通过使用胰蛋白酶，已证明几种大肠杆菌素（E1、E2和K）的作用至少经过两个阶段。第一阶段是大肠杆菌素吸附后的一段时间，此时胰蛋白酶可以恢复经大肠杆菌素处理的细胞的集落形成能力。第一阶段之后是胰蛋白酶无法恢复集落形成能力的时期（第二阶段）。第一阶段和第二阶段之间的转变遵循一级动力学，其速率与吸附的大肠杆菌素杀伤单位数量成正比。对大肠杆菌素K对集落形成能力和几种细胞过程的影响进行的定量比较表明，大肠杆菌素对这些过程的损害发生在大肠杆菌素作用的第二阶段，并且不受在第一阶段恢复细胞活力的胰蛋白酶处理的逆转。讨论了这些发现对理解大肠杆菌素作用模式的意义。
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