BioTechnology Institute and Department of Plant and Microbial Biology, University of Minnesota - Twin Cities, St. Paul, MN, USA.
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, USA.
Mol Microbiol. 2021 Jun;115(6):1069-1079. doi: 10.1111/mmi.14647. Epub 2020 Dec 7.
Shewanella oneidensis is a dissimilatory metal reducing bacterium and model for extracellular electron transfer (EET), a respiratory mechanism in which electrons are transferred out of the cell. In the last 10 years, migration to insoluble electron acceptors for EET has been shown to be nonrandom and tactic, seemingly in the absence of molecular or energy gradients that typically allow for taxis. As the ability to sense, locate, and respire electrodes has applications in bioelectrochemical technology, a better understanding of taxis in S. oneidensis is needed. While the EET conduits of S. oneidensis have been studied extensively, its taxis pathways and their interplay with EET are not yet understood, making investigation into taxis phenomena nontrivial. Since S. oneidensis is a member of an EET-encoding clade, the genetic circuitry of taxis to insoluble acceptors may be conserved. We performed a bioinformatic analysis of Shewanella genomes to identify S. oneidensis chemotaxis orthologs conserved in the genus. In addition to the previously reported core chemotaxis gene cluster, we identify several other conserved proteins in the taxis signaling pathway. We present the current evidence for the two proposed models of EET taxis, "electrokinesis" and flavin-mediated taxis, and highlight key areas in need of further investigation.
希瓦氏菌是一种异化金属还原菌，也是细胞外电子传递（EET）的模式生物，这种呼吸机制是指电子从细胞中转移出来。在过去的 10 年中，已经证明 EET 向不溶性电子受体的迁移并非随机的，而是有策略的，尽管通常情况下，分子或能量梯度允许趋化作用，但这种趋化作用似乎不存在。由于能够感知、定位和呼吸电极在生物电化学技术中有应用，因此需要更好地了解希瓦氏菌中的趋化作用。虽然已经对希瓦氏菌的 EET 通道进行了广泛研究，但它的趋化作用途径及其与 EET 的相互作用尚未被理解，因此对趋化作用现象的研究并非易事。由于希瓦氏菌是编码 EET 的进化枝的成员，因此对不溶性受体的趋化作用的遗传电路可能是保守的。我们对希瓦氏菌属的基因组进行了生物信息学分析，以鉴定保守的趋化作用同源物。除了先前报道的核心趋化作用基因簇外，我们还在趋化作用信号通路中鉴定了几个其他保守蛋白。我们介绍了目前关于 EET 趋化作用的两种模型的证据，即“电动力学”和黄素介导的趋化作用，并强调了需要进一步研究的关键领域。
