Restoration of flagellar clockwise rotation in bacterial envelopes by insertion of the chemotaxis protein CheY.
Restoration of flagellar clockwise rotation in bacterial envelopes by insertion of the chemotaxis protein CheY.
复制标题
通过插入趋化蛋白 CheY 恢复细菌包膜中鞭毛的顺时针旋转。
DOI：
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发表时间：
1986
影响因子：
11.1
通讯作者：
Michael Eisenbach
中科院分区：
文献类型：
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作者：
S. Ravid;Philip MATSUMURAt;Michael Eisenbach
当细菌鼠伤寒沙门氏菌的细胞与青霉素一起孵育并在稀释缓冲液中裂解时，形成无鞭毛细胞质的包膜。当这些膜被鞭毛拴在玻璃上，然后被通电时，它们中的一些就会旋转。野生型封套的旋转方向仅为逆时针（CCW）。我们通过在裂解介质中（因此在包膜中）包括趋化蛋白CheY来扰乱该系统。结果，一些封套仅顺时针（CW）旋转。这样做的信封的分数增加与CheY的浓度;在浓度为48 μ M（pH 8），所有功能的信封旋转CW。在6.6-8.4的范围内，该分数还随着裂解介质的pH而增加。在细胞内Ca ~（2+）存在或不存在的情况下，结果相同。重建信封未能响应趋化刺激。他们都没有改变他们的旋转方向。然而，当细胞内pH值降低到6.6或更低时，顺时针旋转的包膜停止旋转，而逆时针旋转的包膜继续旋转。这种现象是可逆的。我们的结论是，CheY本身，没有任何额外的游离细胞质介质，相互作用的开关在鞭毛的基础上，造成CW旋转。
When cells of the bacterium Salmonella typhimurium are incubated with penicillin and lysed in a dilute buffer, flagellated cytoplasm-free envelopes are formed. When the envelopes are tethered to glass by their flagella and then energized, some of them spin. The direction of rotation of wild-type envelopes is exclusively counterclockwise (CCW). We perturbed this system by including in the lysis medium (and hence in the envelopes) the chemotaxis protein CheY. As a result, some of the envelopes rotated exclusively clockwise (CW). The fraction of envelopes that did so increased with the concentration of CheY; at a concentration of 48 microM (pH 8), all functional envelopes spun CW. The fraction also increased with the pH of the lysis medium in the range of 6.6-8.4. The results were the same in the presence or absence of intracellular Ca2+. Reconstituted envelopes failed to respond to chemotactic stimuli. None of them changed the direction of their rotation. However, when the intracellular pH was lowered to 6.6 or below, envelopes that spun CW stopped rotating, while envelopes that spun CCW continued to rotate. This phenomenon was reversible. We conclude that CheY per se, without any additional free cytoplasmic mediators, interacts with a switch at the base of the flagellum to cause CW rotation.