The alternative role of enterobactin as an oxidative stress protector allows Escherichia coli colony development.
The alternative role of enterobactin as an oxidative stress protector allows Escherichia coli colony development.
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DOI：
10.1371/journal.pone.0084734
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Vincent PA
中科院分区：
文献类型：
--
作者：
Adler C;Corbalan NS;Peralta DR;Pomares MF;de Cristóbal RE;Vincent PA
许多细菌已经进化出不同的铁吸收系统，能够利用它们自己的和异源的铁载体。然而，有越来越多的证据归因于铁载体的替代作用，这可能解释了具有多个铁载体系统的微生物的潜在适应优势。在这项工作中，我们展示了铁载体肠杆菌素在基本培养基中对大肠杆菌菌落发育的要求。我们观察到一株肠杆菌素生产受损的菌株（entE突变株）在M9琼脂培养基上不能形成菌落，而在LB琼脂培养基上生长正常。鉴于铁和柠檬酸盐补充都不能恢复菌落生长，肠杆菌素作为铁吸收促进剂的作用不能解释其对菌落发育的要求。通过添加肠杆菌素、还原剂抗坏血酸或通过在无添加剂的厌氧培养条件下孵育来恢复菌落发育的缺失。然后，我们将菌落发育所需的肠杆菌素与其降低氧化应激的能力相关联，我们发现，与菌株能够形成菌落的培养基（LB）相比，在殖民地发育受损的培养基（M9）中的氧化应激更高。由于oxyR和soxS突变体（两个主要的应激反应调节剂）在M9琼脂培养基中形成菌落，我们假设肠杆菌素可能是氧化应激反应库中的重要组成部分，特别是在菌落形成的背景下。此外，我们表明，肠杆菌素到达细胞质后必须水解，以使菌落发育。通过促进铁释放，肠杆菌素-铁复合物的水解不仅可以确保满足铁的需求，而且还可以为细胞提供具有暴露的羟基的分子（水解的肠杆菌素）。这种分子将能够消除自由基，从而减少氧化应激。
Numerous bacteria have evolved different iron uptake systems with the ability to make use of their own and heterologous siderophores. However, there is growing evidence attributing alternative roles for siderophores that might explain the potential adaptive advantages of microorganisms having multiple siderophore systems. In this work, we show the requirement of the siderophore enterobactin for Escherichia coli colony development in minimal media. We observed that a strain impaired in enterobactin production (entE mutant) was unable to form colonies on M9 agar medium meanwhile its growth was normal on LB agar medium. Given that, neither iron nor citrate supplementation restored colony growth, the role of enterobactin as an iron uptake-facilitator would not explain its requirement for colony development. The absence of colony development was reverted either by addition of enterobactin, the reducing agent ascorbic acid or by incubating in anaerobic culture conditions with no additives. Then, we associated the enterobactin requirement for colony development with its ability to reduce oxidative stress, which we found to be higher in media where the colony development was impaired (M9) compared with media where the strain was able to form colonies (LB). Since oxyR and soxS mutants (two major stress response regulators) formed colonies in M9 agar medium, we hypothesize that enterobactin could be an important piece in the oxidative stress response repertoire, particularly required in the context of colony formation. In addition, we show that enterobactin has to be hydrolyzed after reaching the cell cytoplasm in order to enable colony development. By favoring iron release, hydrolysis of the enterobactin-iron complex, not only would assure covering iron needs, but would also provide the cell with a molecule with exposed hydroxyl groups (hydrolyzed enterobactin). This molecule would be able to scavenge radicals and therefore reduce oxidative stress.
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影响因子：
--
作者：
D'Onofrio A;Crawford JM;Stewart EJ;Witt K;Gavrish E;Epstein S;Clardy J;Lewis K
通讯作者：
Lewis K
影响因子：
4
作者：
Al-Azemi, A.;Fielder, M. D.;Price, R. G.
通讯作者：
Price, R. G.
影响因子：
3.2
作者：
Grass, G;Franke, S;Rensing, C
通讯作者：
Rensing, C
影响因子：
3.2
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通讯作者：
HANTKE, K
影响因子：
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作者：
Kong, IS;Bates, TC;Oliver, JD
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