MISREAD PROTEIN CREATES MEMBRANE CHANNELS - AN ESSENTIAL STEP IN THE BACTERICIDAL ACTION OF AMINOGLYCOSIDES
MISREAD PROTEIN CREATES MEMBRANE CHANNELS - AN ESSENTIAL STEP IN THE BACTERICIDAL ACTION OF AMINOGLYCOSIDES
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DOI：
10.1073/pnas.83.16.6164
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发表时间：
1986-08-01
影响因子：
11.1
通讯作者：
TAI, PC
中科院分区：
文献类型：
--
作者：
DAVIS, BD;CHEN, LL;TAI, PC
在氨基糖苷的多效性作用中，它们不可逆转的摄取和对起始核糖体的阻断似乎解释了它们的杀菌作用，而翻译误读和膜损伤的贡献以及这种损伤的机制仍不确定。我们现在提出的证据表明，将误读的蛋白质结合到膜上可以解释膜的损伤。因此，杀菌作用似乎是由以下顺序产生的，其中每一步都是必不可少的：抗生素的轻微初始进入；与延长链的核糖体的相互作用，导致误读；误读蛋白进入膜，产生异常通道；通过这些通道的进入增加(且不可逆)，从而增加误读和通道的形成；最后，阻止启动的核糖体。这一机制可以解释几个以前未解释的观察结果：链霉素的吸收需要在膜损伤之前的滞后期间但不是之后的蛋白质合成；未能摄取链霉素的链霉素耐药细胞在另一种氨基糖苷类药物处理后可以这样做；中等浓度的嘌呤霉素加速链霉素的吸收，而高浓度(释放较短的链)则阻止它的合成。此外，过早释放正常序列多肽的嘌呤霉素也明显地创造了通道，因为有报道称，即使在链霉素耐药的细胞中，它也能促进链霉素的摄取。这些发现表明，必须选择正常的膜蛋白，不仅是为了形成疏水的锚定表面，也是为了在膜上紧密结合。
Among the pleiotropic effects of aminoglycosides, their irreversible uptake and their blockade of initiating ribosomes have appeared to explain their bactericidal action, while the contributions of translational misreading and membrane damage and the mechanism of that damage have remained uncertain. We now present evidence that incorporated of misread proteins into the membrane can account for the membrane damage. The bactericidal action thus appears to result from the following sequence, in which each step is essential: slight initial entry of the antibiotic; interaction with chain-elongating ribosomes, resulting in misreading; incorporation of misread protein into the membrane, creating abnormal channels; increased (and irreversible) entry through these channels, and hence increased misreading and formation of channels; and, finally, blockade of initiating ribosomes. This mechanism can account for several previously unexplained observations: that streptomycin uptake requires protein synthesis during, but not after, the lag before the membrane damage; that streptomycin-resistant cells, which fail to take up streptomycin, can do so after treatment by another aminoglycoside; and that puromycin at moderate concentrations accelerates streptomycin uptake, while high concentrations (which release shorter chains) prevent it. In addition, puromycin, prematurely releasing polypeptides of normal sequence, also evidently creates channels, since it is reported to promote streptomycin uptake even in streptomycin-resistant cells. These findings imply that normal membrane proteins must be selected not only for a hydrophobic anchoring surface, but also for a tight fit in the membrane.