?-proteobacteria eject their polar flagella under nutrient depletion, retaining flagellar motor relic structures
?-proteobacteria eject their polar flagella under nutrient depletion, retaining flagellar motor relic structures
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β-变形菌在营养耗尽时弹出极鞭毛，保留鞭毛运动遗迹结构
DOI：
10.1101/367458
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Ferreira J
中科院分区：
文献类型：
--
作者：
Ferreira J
在有利的条件下，细菌只会间歇性地转变为能动的非稳态生活方式。然而，在长期营养缺乏的情况下，细菌会精心安排一个转换到静止期，通过改变新陈代谢和停止运动来保存能量。大约三分之二的细菌使用鞭毛游泳，但细菌如何使这个大分子机器失活仍不清楚。在这里，我们描述了以前未报道的喷射极性电机的γ-变形菌。我们发现，这些细菌弹出鞭毛钩的基础上，营养物质耗尽时，留下一个遗迹的前鞭毛电机的外膜。全电机和遗物的subtomography平均值显示，这是一个活跃的过程，作为塞蛋白出现在遗物中，可能会防止泄漏通过其外膜;此外，我们表明，喷射触发下营养耗尽，是独立的细丝作为一个可能的mechanosensor。我们发现，丝状体喷射是一种普遍现象，在不同的γ-变形菌中，包括类志贺邻单胞菌、霍乱弧菌、费氏弧菌、腐败希瓦氏菌和铜绿假单胞菌，其遗迹结构的出现证明了丝状体喷射的存在。虽然分子细节仍有待确定，但我们的研究结果证明了细菌在营养物质稀缺时停止昂贵运动的新机制。
Bacteria switch only intermittently to motile planktonic lifestyles under favorable conditions. Under chronic nutrient deprivation, however, bacteria orchestrate a switch to stationary phase, conserving energy by altering metabolism and stopping motility. About two-thirds of bacteria use flagella to swim, but how bacteria deactivate this large molecular machine remains unclear. Here, we describe the previously unreported ejection of polar motors by γ-proteobacteria. We show that these bacteria eject their flagella at the base of the flagellar hook when nutrients are depleted, leaving a relic of a former flagellar motor in the outer membrane. Subtomogram averages of the full motor and relic reveal that this is an active process, as a plug protein appears in the relic, likely to prevent leakage across their outer membrane; furthermore, we show that ejection is triggered only under nutritional depletion and is independent of the filament as a possible mechanosensor. We show that filament ejection is a widespread phenomenon demonstrated by the appearance of relic structures in diverse γ-proteobacteria includingPlesiomonas shigelloides,Vibrio cholerae,Vibrio fischeri,Shewanella putrefaciens, andPseudomonas aeruginosa. While the molecular details remain to be determined, our results demonstrate a novel mechanism for bacteria to halt costly motility when nutrients become scarce.