AEROTAXIS IN SALMONELLA-TYPHIMURIUM - ROLE OF ELECTRON-TRANSPORT
AEROTAXIS IN SALMONELLA-TYPHIMURIUM - ROLE OF ELECTRON-TRANSPORT
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DOI：
10.1128/jb.145.2.990-1001.1981
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发表时间：
1981-01-01
影响因子：
3.2
通讯作者：
TAYLOR, BL
中科院分区：
文献类型：
--
作者：
LASZLO, DJ;TAYLOR, BL
趋氧性中的感觉转导需要电子传递，而趋化性则不依赖于电子传递。通过采用独立于呼吸的空间和时间O2梯度开发了趋氧性测定。通过改变时间测定中O2浓度的阶跃增加，获得了S.鼠伤寒。在0.4 μ M O2下的半最大响应和5 mM KCN的抑制表明，趋氧性的受体是细胞色素o。这种反应与氧化磷酸化形成ATP无关，但与荧光花青染料diS-C3-（5）监测的膜电位变化相关。硝酸盐和富马酸盐是呼吸链的电子受体。当硝酸还原酶和延胡索酸还原酶被诱导时，鼠伤寒杆菌抑制嗜氧性。这些结果支持的假设，出租车O2，硝酸盐和富马酸盐介导的电子传递系统和质子动力的变化。在tsr、tar或trg基因缺陷的大肠杆菌突变体中，嗜氧性是正常的;鼠伤寒沙门氏菌，O2没有刺激这些基因的产物甲基化。A. cheC突变体对化学引诱物表现出相反的反应，对O2也表现出相反的反应。趋气性是由一个独特的和身份不明的信号蛋白转导，但集中到共同的化学感受途径之前，涉及cheC产品的步骤。当S.当鼠伤寒沙门氏菌变为厌氧时，糖酵解引起的质子动力降低支持缓慢游泳，但不支持翻滚，表明翻滚需要最小的质子动力。细菌迅速适应了厌氧条件，并在约10分钟后恢复翻滚。当细菌先前在厌氧条件下生长时，适应期短得多。
Sensory transduction in aerotaxis required electron transport, in contrast to chemotaxis, which is independent of electron transport. Assays for aerotaxis were developed by employing spatial and temporal O2 gradients imposed independently of respiration. By varying the step increase in O2 concentration in the temporal assay, the dose-response relationship was obtained for aerotaxis in S. typhimurium. A half-maximal response at 0.4 .mu.M O2 and inhibition by 5 mM KCN suggested that the receptor for aerotaxis is cytochrome o. The response was independent of ATP formation via oxidative phosphorylation, but correlated with changes in membrane potential monitored with the fluorescent cyanine dye diS-C3-(5). Nitrate and fumarate, which are alternative electron acceptors for the respiratory chain in S. typhimurium, inhibited aerotaxis when nitrate reductase and fumarate reductase were induced. These results support the hypothesis that taxis to O2, nitrate and fumarate is mediated by the electron transport system and by changes in the proton motive force. Aerotaxis was normal in Escherichia coli mutants that were defective in the tsr, tar or trg genes; in S. typhimurium, O2 did not stimulate methylation of the products of these genes. A. cheC mutant which shows an inverse response to chemoattractants also gave an inverse response to O2. Aerotaxis is transduced by a distinct and unidentified signalling protein but is focused into the common chemosensory pathway before the step involving the cheC product. When S. typhimurium became anaerobic, the decreased proton motive force from glycolysis supported slow swimming but not tumbling, indicating that a minimum proton motive force was required for tumbling. The bacteria rapidly adapted to the anaerobic condition and resumed tumbling after .apprx. 3 min. The adaptation period was much shorter when the bacteria were previously grown anaerobically.