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首页> 外文期刊>Journal of bacteriology >Roles of Chemosensory Pathways in Transient Changes in Swimming Speed of Rhodobacter sphaeroides Induced by Changes in Photosynthetic Electron Transport
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Roles of Chemosensory Pathways in Transient Changes in Swimming Speed of Rhodobacter sphaeroides Induced by Changes in Photosynthetic Electron Transport

机译:光合电子传输变化诱导的乳椎素瓣椎间盘突鼻腔瞬态变化中的化学感应途径

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摘要

The response of free-swimming Rhodobacter sphaeroidesto increases and decreases in the intensity of light of different wavelengths was analyzed. There was a transient (1 to 2 s) increase in swimming speed in response to an increase in light intensity, and there was a similar transient stop when the light intensity decreased. Measurement of changes in membrane potential and the use of electron transport inhibitors showed that the transient increase in swimming speed, following an increase in light intensity, and the stop following its decrease were the result of changes in photosynthetic electron transport. R. sphaeroides has two operons coding for multiple homologs of the enteric chemosensory genes. Mutants in the first chemosensory operon showed wild-type photoresponses. Mutants with the cheA gene of the second operon (cheA II) deleted, either with or without the first operon present, showed inverted photoresponses, with free-swimming cells stopping on an increase in light intensity and increasing swimming speed on a decrease. These mutants also lacked adaptation. Transposon mutants with mutations incheA II, which also reduced expression of downstream genes, however, showed no photoresponses. These results show that (i) free-swimming cells respond to both an increase and a decrease in light intensity (tethered cells only show the stopping on a step down in light intensity), (ii) the signal comes from photosynthetic electron transfer, and (iii) the signal is primarily channelled through the second chemosensory pathway. The different responses shown by thecheA II deletion and insertion mutants suggest that CheWII is required for photoresponses, and a third sensory pathway can substitute for CheAII as long as CheWII is present. The inverted response suggests that transducers are involved in photoresponses as well as chemotactic responses.
机译:分析了自由游泳乳菌氏菌氏菌的响应在不同波长光的光线强度增加和减小。游泳速度的瞬态(1至2秒)响应于光强度的增加,并且当光强度降低时存在类似的瞬态止动件。膜电位变化的测量和电子传输抑制剂的使用表明,在光强度的增加之后,游泳速度的瞬态增加,并且在其下降之后的停止是光合电子传输的变化的结果。 R. Sphaeroides 有两个编码肠溶化学感性基因的多种同源物。第一化学感染术中的突变体显示出野生型光反对子。突变与第二款式的 Chea 基因的突变体( chea ii ii ),无论是在所有情况下的,都显示出倒的光响应,自由游泳的电池停止增加光强度,增加游泳速度减少。这些突变体也缺乏适应性。然而,在 Chea II℃下的突变的转座突变体也没有减少下游基因的表达,显示出不容称。这些结果表明,(i)自由游泳细胞响应增加,光强度的降低(束缚电池仅在光强度下降下降),(ii)信号来自光合电子转移,以及(iii)信号主要通过第二化学感应途径引导。 chea ii 删除和插入突变体显示的不同响应表明,光响应呼应需要咀嚼 ii ,第三个感觉途径可以替代只要存在咀嚼 II ,Chea II 存在。倒置响应表明换能器参与光响应和趋化反应。

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