从宿主获取金属离子
中文名称
通路描述
在好氧条件下，铁离子以 Fe3+ 形式复合物化，而在厌氧或酸性环境中，铁以更可溶的形式 Fe2+ 存在。肠杆菌已发展出机制从环境中收集这两种类型的铁，相关的基因特别见于致病菌株（Miethke & Marahiel 2007, Wilson et al. 2016, Palmer & Skaar 2016）。外源性血红素被溶血素降解促进铁利用。除了获取游离铁外，肠杆菌摄取并降解血红素（综述见 Caza & Kronstadt, 2013）。其他通过不同机制从宿主获取的必需金属离子还包括 Zn2+, Mn2+, Co2+, Ni2+ 和 Cu2+（Koh et al., 2015; 综述见 Palmer & Skaar）。除了金属离子的直接进口外，主要获取机制是外部离子与高亲和力螯合剂的复合物化，随后导入相应的复合物。在 E.coli 中构象表达的是螯合剂肠杆菌素和羟基酸。致病菌株通常并额外合成和利用耶尔森菌素、气杆菌素和/或沙尔莫林（综述见 Braun & Braun, 2002; Miethke & Marahiel 2007）。
英文描述
Metal ion assimilation from the host In aerobic conditions iron ions are complexed as Fe3+, while in anaerobic or acidic environments iron is encountered in its more soluble form Fe2+. Enterobacteria have developed mechanisms to collect both types of iron from the environment, and the genes involved are especially seen in pathogenic strains (Miethke & Marahiel 2007, Wilson et al. 2016, Palmer & Skaar 2016). External degradation of heme by hemolysins facilitates iron assimilation. In addition to the acquisition of free iron, enterobacteria take up and degrade heme (reviewed in Caza & Kronstadt, 2013). Other essential metal ions that are acquired from the host using distinct mechanisms are Zn2+, Mn2+, Co2+, Ni2+ and Cu2+ (Koh et al., 2015; reviewed in Palmer & Skaar). Apart from direct import of metal ions, the main mechanism of acquisition is complexation of external ions with high-affinity siderophores and subsequent import of the respective complexes. Constitutionally expressed in E.coli are the siderophores enterobactin and hydroxamate. Pathogenic strains usually and additionally synthesize and utilize yersiniabactin, aerobactin, and/or salmochelin (reviewed in Braun & Braun, 2002; Miethke & Marahiel 2007).
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