Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers
Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers
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DOI：
10.1016/j.cell.2019.03.029
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发表时间：
2019-04-04
期刊：
影响因子：
64.5
通讯作者：
Malvankar, Nikhil S.
中科院分区：
文献类型：
--
作者：
Wang, Fengbin;Gu, Yangqi;Malvankar, Nikhil S.
长距离（>10 μ m）传输的电子沿着网络的Geoclussulfreducens蛋白丝，被称为微生物纳米线，已被调用来解释广泛的全球重要的氧化还原现象。这些纳米线以前被认为是由PilA蛋白组成的IV型皮利。在这里，我们报告了一个3.7埃分辨率的冷冻电子显微镜结构，这令人惊讶地揭示，而不是PilA，G。硫还原物纳米线通过六血红素细胞色素OmcS的微米长聚合来组装，其中血红素彼此堆积在近似3.5-6埃的范围内。亚基间界面显示出独特的结构元件，例如亚基间平行堆叠的房屋以及邻近亚基的组氨酸对血红素的轴向配位。野生型OmcS细丝显示出比来自Delta OmcS菌株的其他细丝大100倍的电导率，突出了OmcS对这些纳米线中电导率的重要性。这种结构解释了土壤细菌将电子传输到远程电子受体进行呼吸和能量共享的显着能力。
Long-range (>10 mu m) transport of electrons along networks of Geobacter sulfurreducens protein filaments, known as microbial nanowires, has been invoked to explain a wide range of globally important redox phenomena. These nanowires were previously thought to be type IV pili composed of PilA protein. Here, we report a 3.7 angstrom resolution cryoelectron microscopy structure, which surprisingly reveals that, rather than PilA, G. sulfurreducens nanowires are assembled by micrometer-long polymerization of the hexaheme cytochrome OmcS, with hemes packed within similar to 3.5-6 angstrom of each other. The inter-subunit interfaces show unique structural elements such as inter-subunit parallel-stacked homes and axial coordination of heme by histidines from neighboring subunits. Wild-type OmcS filaments show 100-fold greater conductivity than other filaments from a Delta omcS strain, highlighting the importance of OmcS to conductivity in these nanowires. This structure explains the remarkable capacity of soil bacteria to transport electrons to remote electron acceptors for respiration and energy sharing.