Indole Production Promotes Escherichia coli Mixed-Culture Growth with Pseudomonas aeruginosa by Inhibiting Quorum Signaling
Indole Production Promotes Escherichia coli Mixed-Culture Growth with Pseudomonas aeruginosa by Inhibiting Quorum Signaling
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DOI：
10.1128/aem.06396-11
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发表时间：
2012-01-01
影响因子：
4.4
通讯作者：
McLean, Robert J. C.
中科院分区：
文献类型：
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作者：
Chu, Weihua;Zere, Tesfalem R.;McLean, Robert J. C.
20世纪初发现的大肠杆菌产生吲哚，已被用作区分大肠杆菌和其他肠道细菌的诊断标志。通过对已定义突变体的转录图谱和竞争研究，我们表明环腺苷(CAMP)调控的吲哚形成是使大肠杆菌在具有铜绿假单胞菌的混合生物膜和浮游种群中生长的主要因素。在与铜绿假单胞菌共培养时，缺乏cAMP产生(CAMP)或cAMP受体基因(CRP)和吲哚产生(TNAA)的突变体不具有竞争性，但可以通过补充生理上相关的吲哚浓度来恢复野生型竞争力。缺乏吲哚和N-酰基高丝氨酸内酯(AHLS)受体的大肠杆菌sdiA突变体在竞争适应性方面没有变化，这表明吲哚直接作用于铜绿假单胞菌。一株大肠杆菌tna A突变株与铜绿假单胞菌AHL合成酶(rhlI和rhlI LASI)突变株一起生长，恢复了野生型竞争能力。与野生型相比，铜绿假单胞菌AHL合酶突变体不能降解吲哚。混合培养过程中产生的吲哚抑制铜绿假单胞菌绿青素的产生和其他AHL调节的毒力因子。与铜绿假单胞菌的混合培养促进了不能调节cAMP水平的大肠杆菌cpdA中吲哚的形成，这表明混合培养的基因可能通过cAMP激活。这些发现说明了吲哚是如何通过抑制铜绿假单胞菌中群体调节的竞争因子在混合培养存活中发挥重要作用的。吲哚是早期描述的大肠杆菌中心代谢的特征。
Indole production by Escherichia coli, discovered in the early 20th century, has been used as a diagnostic marker for distinguishing E. coli from other enteric bacteria. By using transcriptional profiling and competition studies with defined mutants, we show that cyclic AMP (cAMP)-regulated indole formation is a major factor that enables E. coli growth in mixed biofilm and planktonic populations with Pseudomonas aeruginosa. Mutants deficient in cAMP production (cyaA) or the cAMP receptor gene (crp), as well as indole production (tnaA), were not competitive in coculture with P. aeruginosa but could be restored to wild-type competitiveness by supplementation with a physiologically relevant indole concentration. E. coli sdiA mutants, which lacked the receptor for both indole and N-acyl-homoserine lactones (AHLs), showed no change in competitive fitness, suggesting that indole acted directly on P. aeruginosa. An E. coli tnaA mutant strain regained wild-type competiveness if grown with P. aeruginosa AHL synthase (rhlI and rhlI lasI) mutants. In contrast to the wild type, P. aeruginosa AHL synthase mutants were unable to degrade indole. Indole produced during mixed-culture growth inhibited pyocyanin production and other AHL-regulated virulence factors in P. aeruginosa. Mixed-culture growth with P. aeruginosa stimulated indole formation in E. coli cpdA, which is unable to regulate cAMP levels, suggesting the potential for mixed-culture gene activation via cAMP. These findings illustrate how indole, an early described feature of E. coli central metabolism, can play a significant role in mixed-culture survival by inhibiting quorum-regulated competition factors in P. aeruginosa.