The growth response of Escherichia coli to neurotransmitters and related catecholamine drugs requires a functional enterobactin biosynthesis and uptake system
The growth response of Escherichia coli to neurotransmitters and related catecholamine drugs requires a functional enterobactin biosynthesis and uptake system
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DOI：
10.1128/iai.70.11.5913-5923.2002
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发表时间：
2002-11-01
影响因子：
3.1
通讯作者：
Williams, P
中科院分区：
文献类型：
--
作者：
Burton, CL;Chhabra, SR;Williams, P
神经递质去甲肾上腺素(NE)刺激低接种量的大肠杆菌在添加血清(SAPI+血清)的最低浓度(SAPI)中生长，并诱导“自身诱导物”(AI)的产生，从而在没有NE的情况下促进大肠杆菌的生长。鉴于去甲肾上腺素、肾上腺素及其相应的肾上腺素能激动剂和拮抗剂在临床医学中的重要性，我们试图调查这些观察的分子基础。利用多种去甲肾上腺素前体、代谢物和治疗剂，我们证明了它们在SAPI+血清中刺激大肠杆菌生长的能力依赖于儿茶酚(1，2-二苯酚)部分的存在，该部分的最大活性需要一个含有末端伯胺的两碳取代基。血清中含有铁结合糖蛋白-转铁蛋白，当SAPI+血清中添加足够的Fe3+饱和转铁蛋白时，生长抑制被解除。其他金属阳离子，包括镁、钙和锌离子，没有影响。这些数据表明，在SAPI+血清中NE对大肠杆菌生长的刺激作用可能与2，3-二羟基苯甲酰丝氨酸的环状三酯--儿茶酚类铁载体有关。与这一假设一致的是，具有铁肠结合蛋白运输(FepA或TonB)或肠结合蛋白生物合成(Enta)突变的大肠杆菌菌株对去甲肾上腺素没有反应。此外，在生长过程中，NE诱导SAPI+血清中铁结合蛋白受体FepA的表达。肠杆菌素降解产物2，3-二羟基苯甲酰丝氨酸(DBS)与去甲肾上腺素(NE)对大肠杆菌生长的刺激作用相同，而FepA或TonB突变取消了DBS依赖的生长刺激。然而，与NE相反，DBS刺激了Enta突变体的生长。此外，大肠杆菌Enta(+)亲本的乙酸乙酯提取物在不含NE的限铁M9培养基中生长后，其乙酸乙酯提取物中含有AI，即在SAPI+血清中刺激大肠杆菌的生长。综上所述，这些数据表明，当低数量的大肠杆菌被接种到SAPI+血清中时，NE、DBS和相关的儿茶酚胺诱导肠道活蛋白铁摄取系统。这反过来促进了铁从转铁蛋白中的隔离，并表明存在于NE条件SAPI+血清培养液中的AI是Enterobactin及其DBS分解产物。
The neurotransmitter norepinephrine (NE) stimulates the growth of low inocula of Escherichia coli in a minimal medium (SAPI) supplemented with serum (SAPI+serum) and induces the production of an "autoinducer" (AI) which, in turn, promotes E. coli growth in the absence of NE. Given the importance of NE, epinephrine, and their corresponding adrenergic agonists and antagonists in clinical medicine, we sought to investigate the molecular basis for these observations. Using a variety of NE precursors, metabolites, and therapeutic agents, we demonstrated that their ability to stimulate E. coli growth in SAPI +serum is dependent on the presence of a catechol (1,2-dihydroxybenzene) moiety with maximal activity requiring a two-carbon substituent incorporating a terminal primary amine. Serum contains the iron-binding glycoprotein, transferrin, and when SAPI+sermn was supplemented with sufficient Fe3+ to saturate transferrin, growth inhibition was relieved. Other metal cations, including Mg2+, Ca2+, and Zn2+, had no effect. These data suggested that the stimulation of E. coli growth by NE in SAPI+serum may involve the catecholate siderophore, enterobactin, a cyclic triester of 2,3-dihydroxybenzoylserine. Consistent with this hypothesis, E. coli strains with mutations in ferrienterobactin transport (fepA or tonB) or enterobactin biosynthesis (entA) did not respond to NE. Furthermore, NE induced expression of the ferrienterobactin receptor, FepA, during growth in SAPI+serum. The enterobactin degradation product, 2,3-dihydroxybenzoylserine (DBS) was as effective as NE in stimulating the growth of E. coli and mutations in fepA or tonB abolished the DBS-dependent growth stimulation. In contrast to NE, however, DBS stimulated the growth of the entA mutant. Moreover, after growth in an iron-limited M9 medium in the absence of NE, ethyl acetate extracts of the E. coli entA(+) parent but not of the entA+ mutant contained AI, i.e., stimulated the growth of E. coli in SAPI+serum. Taken together, these data show that when low numbers of E. coli are inoculated into SAPI+serum, NE, DBS, and related catecholamines induce the enterobactin iron uptake system. This, in turn, facilitates iron sequestration from transferrin and indicates that the AI present in NE-conditioned SAPI+serum medium is enterobactin and its DBS breakdown products.