Regulation of Indole Signalling during the Transition of E. coli from Exponential to Stationary Phase.
Regulation of Indole Signalling during the Transition of E. coli from Exponential to Stationary Phase.
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DOI：
10.1371/journal.pone.0136691
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Summers D
中科院分区：
文献类型：
--
作者：
Gaimster H;Summers D
在从指数相到稳定期的转变过程中，大肠杆菌产生了大量的小分子芳香信号分子吲哚。在LB介质中，上清液吲哚浓度最高可达0.5-1 mm。在这个浓度下，吲哚参与了许多诱导耐酸和毒力调节的过程。最近的研究表明，与细胞相关的吲哚会瞬间达到很高的浓度(约。60 mm)，可能是因为吲哚的产生速度比离开细胞的速度快。这种吲哚脉冲抑制生长和细胞分裂，使培养物在营养物质完全耗尽之前进入稳定期，有利于在长期稳定期存活。这项研究询问了大肠杆菌细胞如何在进入静止阶段时迅速上调吲哚的产生，以及为什么吲哚脉冲的持续时间只有10-15分钟。我们发现，在脉冲开始时，色氨酸酶的合成是由葡萄糖耗竭触发的，这与吲哚合成的上调有关。由此产生的吲哚脉冲的大小和持续时间取决于外源色氨酸的可用性。当所有可用的色氨酸耗尽，与细胞相关的吲哚与上清液平衡时，吲哚的产生就停止了。
During the transition from exponential to stationary phase E. coli produces a substantial quantity of the small, aromatic signalling molecule indole. In LB medium the supernatant indole concentration reaches a maximum of 0.5–1 mM. At this concentration indole has been implicated in many processes inducing acid resistance and the modulation of virulence. It has recently been shown that cell-associated indole transiently reaches a very high concentration (approx. 60 mM) during stationary phase entry, presumably because indole is being produced more rapidly than it can leave the cell. It is proposed that this indole pulse inhibits growth and cell division, causing the culture to enter stationary phase before nutrients are completely exhausted, with benefits for survival in long-term stationary phase. This study asks how E. coli cells rapidly upregulate indole production during stationary phase entry and why the indole pulse has a duration of only 10–15 min. We find that at the start of the pulse tryptophanase synthesis is triggered by glucose depletion and that this is correlates with the up-regulation of indole synthesis. The magnitude and duration of the resulting indole pulse are dependent upon the availability of exogenous tryptophan. Indole production stops when all the available tryptophan is depleted and the cell-associated indole equilibrates with the supernatant.