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Abstract：
Iron (Fe) is the fourth most abundant element in the Earth\'s crust where ferrous Fe [Fe(II)] and ferric Fe [Fe(III)] can be used by archaea for energy conservation. In these archaea-Fe interactions, Fe(III) serves as terminal electron acceptor for anaerobic respiration by a variety of archaea, while Fe(II) serves as electron donor and/or energy sources for archaeal growth. As no Fe is incorporated into the archaeal cells, these redox reactions are referred to as dissimilatory Fe(III) reduction and Fe(II) oxidation, respectively. Dissimilatory Fe(III)-reducing archaea (FeRA) and Fe(II)-oxidizing archaea (FeOA) are widespread on Earth where they play crucial roles in biogeochemical cycling of not only Fe, but also carbon and sulfur. To reduce extracellular Fe(III) (oxyhydr)oxides, some FeRA transfer electrons directly to the Fe(III) (oxyhydr)oxides most likely via multiheme c-type cytochromes (c-Cyts). These multiheme c-Cyts may form the pathways similar to those found in bacteria for transferring electrons from the quinone/quinol pool in the cytoplasmic membrane to the Fe(III) (oxyhydr)oxides external to the archaeal cells. Use of multiheme c-Cyts for extracellular Fe(III) reduction by both Domains of Archaea and Bacteria emphasizes an ancient mechanism of extracellular electron transfer, which is well conserved. Other FeRA, however, reduce Fe(III) (oxyhydr)oxides indirectly via electron shuttles. Similarly, it is proposed that FeOA use pathways to oxidize Fe(II) on the surface of the cytoplasmic membrane and then to transfer the released electrons across the cytoplasmic membrane inward to the O2 and NAD+ in the cytoplasm. In this review, we focus on the latest understandings of the molecular mechanisms used by FeRA and FeOA for Fe(III) reduction and Fe(II) oxidation, respectively.
摘要：
铁（Fe）是地壳中第四丰富的元素，其中铁[Fe（II）]和铁[Fe（III）]可被古细菌用于节能。在这些古细菌-铁相互作用中，Fe（III）充当各种古细菌厌氧呼吸的末端电子受体，而Fe（II）充当古细菌生长的电子供体和/或能源。由于没有铁掺入古细菌细胞，这些氧化还原反应被称为异化Fe（III）还原和Fe（II）氧化，分别。异化的Fe（III）还原古细菌（FeRA）和Fe（II）氧化古细菌（FeOA）在地球上普遍存在，它们不仅在Fe的生物地球化学循环中起着至关重要的作用。还有碳和硫.为了减少细胞外Fe（III）（氧化氢）氧化物，一些FeRA最可能通过多血红素c型细胞色素（c-Cyts）将电子直接转移到Fe（III）（氧化氢）氧化物。这些多血红素c-Cyts可能形成与细菌中发现的途径相似的途径，用于将电子从胞质膜中的醌/喹啉池转移到古细菌细胞外部的Fe（III）（氧化氢）氧化物。古菌和细菌域使用多血红素c-Cyts还原细胞外Fe（III）强调了细胞外电子转移的古老机制，这是非常保守的。其他FeRA,然而,通过电子穿梭间接还原Fe（III）（氧化氢）氧化物。同样，建议FeOA使用途径氧化细胞质膜表面上的Fe（II），然后将释放的电子穿过细胞质膜向内转移到细胞质中的O2和NAD。在这次审查中,我们专注于对FeRA和FeOA用于Fe（III）还原和Fe（II）氧化的分子机制的最新理解，分别。
