Abuyen Karla, El-Naggar Mohamed Y
Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089.
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089.
ChemElectroChem. 2023 Feb 13;10(4). doi: 10.1002/celc.202200965. Epub 2023 Jan 11.
Extracellular electron transfer (EET) is a process that microorganisms use to reduce or oxidize external insoluble electron acceptors or donors. Much of our mechanistic understanding of this process is derived from studies of transmembrane cytochrome complexes and extracellular redox shuttles that mediate outward EET to anodes and external electron acceptors. In contrast, there are knowledge gaps concerning the reverse process of inward EET from external electron donors to cells. Here, we describe a role for soluble iron (exogenous FeCl) in enhancing EET from cathodes to the model EET bacterium MR-1, with fumarate serving as the intracellular electron acceptor. This iron concentration-dependent electron uptake was eradicated upon addition of an iron chelator and occurred only in the presence of fumarate reductase, confirming an electron pathway from cathodes to this periplasmic enzyme. Moreover, mutants lacking specific outer membrane and periplasmic cytochromes exhibited significantly decreased current levels relative to wild-type. These results indicate that soluble iron can function as an electron carrier to the EET machinery of .
细胞外电子转移（EET）是微生物用于还原或氧化外部不溶性电子受体或供体的过程。我们对这一过程的许多机理理解来自于对跨膜细胞色素复合物和细胞外氧化还原穿梭体的研究，这些复合物和穿梭体介导向外的EET至阳极和外部电子受体。相比之下，关于从外部电子供体到细胞的向内EET的反向过程存在知识空白。在此，我们描述了可溶性铁（外源FeCl）在增强从阴极到模式EET细菌MR-1的EET中的作用，其中富马酸酯作为细胞内电子受体。添加铁螯合剂后，这种铁浓度依赖性的电子摄取被消除，并且仅在存在富马酸还原酶的情况下发生，证实了从阴极到这种周质酶的电子途径。此外，缺乏特定外膜和周质细胞色素的突变体相对于野生型表现出显著降低的电流水平。这些结果表明可溶性铁可以作为电子载体作用于 的EET机制。
