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Cryo-EM of the OmcS nanowires from Geobacter sulfurreducens
Structural highlights
FunctionOMCS_GEOSL Plays an important role in extracellular electron transfer. Can transfer electrons to insoluble Fe(3+) oxides as well as other extracellular electron acceptors, including Mn(4+) oxide and humic substances (PubMed:16332857, PubMed:20400557, PubMed:21236241). Essential for direct interspecies electron transfer (DIET) in cocultures with G. metallireducens (PubMed:23377933).[1] [2] [3] [4] Publication Abstract from PubMedLong-range (>10 mum) 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 A 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 approximately 3.5-6 A of each other. The inter-subunit interfaces show unique structural elements such as inter-subunit parallel-stacked hemes and axial coordination of heme by histidines from neighboring subunits. Wild-type OmcS filaments show 100-fold greater conductivity than other filaments from a DeltaomcS 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. Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers.,Wang F, Gu Y, O'Brien JP, Yi SM, Yalcin SE, Srikanth V, Shen C, Vu D, Ing NL, Hochbaum AI, Egelman EH, Malvankar NS Cell. 2019 Apr 4;177(2):361-369.e10. doi: 10.1016/j.cell.2019.03.029. PMID:30951668[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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