Physiological and Proteomic Analysis of Escherichia coli Iron-Limited Chemostat Growth
Physiological and Proteomic Analysis of Escherichia coli Iron-Limited Chemostat Growth
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DOI：
10.1128/jb.01606-14
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发表时间：
2014-08-01
影响因子：
3.2
通讯作者：
Carlson, Ross P.
中科院分区：
文献类型：
--
作者：
Folsom, James Patrick;Parker, Albert E.;Carlson, Ross P.
铁的生物利用度是哺乳动物宿主组织中细菌生长的主要限制因素，因此代表了一个重要的研究领域。大肠杆菌K-12代谢进行了研究，在四个水平的铁限制在恒化器中使用生理和蛋白质组学分析。数据记录了一个E.大肠杆菌驯化梯度，其中逐渐更严重的铁缺乏导致更大百分比的底物碳被引导到溢流代谢中，伴随着葡萄糖上的生物质产量的降低。醋酸盐是中等水平铁限制的主要分泌有机副产物，但随着应激的增加，代谢转变为主要分泌乳酸盐（类似于70%的分解代谢葡萄糖碳）。蛋白质组学分析加强了生理数据和量化的相对增加糖酵解酶丰度和减少三羧酸（TCA）循环酶丰度增加铁限制应力。综合数据表明，E.大肠杆菌通过将稀缺资源投入必需酶来响应限制铁，以分解代谢效率为代价（即，下调含有大量铁需求的酶的高ATP产生途径，如TCA循环）。驯化铁限制的增长进行了对比实验驯化葡萄糖限制的增长，以确定一般和营养特定的驯化策略。虽然铁限制的文化最大化的生物质产量的铁和铁收购策略的表达增加，葡萄糖限制的文化最大化的生物质产量的葡萄糖和碳收购策略的表达增加。本研究量化了营养限制的生态竞争性驯化，产生了了解医学相关的细菌对宿主的反应和制定干预策略所必需的知识。
Iron bioavailability is a major limiter of bacterial growth in mammalian host tissue and thus represents an important area of study. Escherichia coli K-12 metabolism was studied at four levels of iron limitation in chemostats using physiological and proteomic analyses. The data documented an E. coli acclimation gradient where progressively more severe iron scarcity resulted in a larger percentage of substrate carbon being directed into an overflow metabolism accompanied by a decrease in biomass yield on glucose. Acetate was the primary secreted organic by-product for moderate levels of iron limitation, but as stress increased, the metabolism shifted to secrete primarily lactate (similar to 70% of catabolized glucose carbon). Proteomic analysis reinforced the physiological data and quantified relative increases in glycolysis enzyme abundance and decreases in tricarboxylic acid (TCA) cycle enzyme abundance with increasing iron limitation stress. The combined data indicated that E. coli responds to limiting iron by investing the scarce resource in essential enzymes, at the cost of catabolic efficiency (i.e., downregulating high-ATP-yielding pathways containing enzymes with large iron requirements, like the TCA cycle). Acclimation to iron-limited growth was contrasted experimentally with acclimation to glucose-limited growth to identify both general and nutrient-specific acclimation strategies. While the iron-limited cultures maximized biomass yields on iron and increased expression of iron acquisition strategies, the glucose-limited cultures maximized biomass yields on glucose and increased expression of carbon acquisition strategies. This study quantified ecologically competitive acclimations to nutrient limitations, yielding knowledge essential for understanding medically relevant bacterial responses to host and to developing intervention strategies.