New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph
New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph
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DOI：
10.1128/aem.01374-15
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发表时间：
2015-09-01
影响因子：
4.4
通讯作者：
Edwards, Katrina J.
中科院分区：
文献类型：
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作者：
Barco, Roman A.;Emerson, David;Edwards, Katrina J.
微好氧、嗜中性、氧化铁细菌(FeOB)是通过还原的Fe(II)在中性或接近中性的pH条件下，在氧气的存在下被氧化而生长的，这使得它们与许多Fe(II)浓度升高的环境相关。然而，这些中性FeOB氧化Fe(II)的生化机制尚不清楚，这一过程的遗传标记也是不可用的。在海洋中，泽塔变形杆菌属的嗜氧微生物是唯一已知的以化学自养方式氧化铁并同时以扭曲的氢氧化铁茎的形式生物矿化的微生物。本研究的目的是鉴定与嗜氧、嗜中性FeOB的电子传输链相关的高表达蛋白质。为此，我们培养了海洋铁氧菌PV-1，提取其蛋白质，测定其氧化还原活性，并用液相色谱-串联质谱仪对其进行多肽鉴定。结果表明，细胞色素c(4)、CBB(3)型细胞色素氧化酶亚基和外膜细胞色素c是最高表达的蛋白质，表明它们参与了细菌铁的好氧、中性氧化过程。与替代复合体III、磷酸盐运输、碳固定和生物膜形成相关的蛋白质丰富，与马里奥菲斯的生活方式一致。
Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c(4), cbb(3)-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus.