User:Nikhil Malvankar/Cytochrome nanowires
Interactive 3D Complement in Proteopedia
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Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers[1].
Fengbin Wang,
Yanqui Gu,
J. Patrick O'Brien,
Sophia M. Yi,
Sibel Ebru Yalcin,
Vishok Srikanth,
Cong Shen,
Dennis Vu,
Nicole L. Ing,
Allon I. Hochbaum,
Edward H. Egelman,
and
Nikhil S. Malvankar.
Cell 177:361-9,
April 4, 2019. doi:10.1016/j.cell.2019.03.029
Structure TourStructure Tour
BackgroundThe electrically conductive nanowires that extend from cells of Geobacter sulfurreducens have long been thought to be pili assembled from PilA protein. However, the evidence was indirect. Here, the structure of filaments of wild type Geobacter sulfurreducens, confirmed to be electrically conductive, was determined by cryo-electron microscopy (6ef8)[1]. Surprisingly, these nanowires are assembled from outer membrane cytochrome OmcS. These findings were confirmed a short time later (6nef)[2]. Nanowire StructureA nanowire model composed of 7 OmcS protein chains, each shown a different color, was constructed from the 3.2-3.7 Å cryo-EM density (). The filament is ~4 nm in diamater, and has a characteristic undulating or sinusoidal form with a wavelength (pitch) of ~20 nm. The OmcS monomers have 407 amino acids each. The .
The amino terminus forms a bulge that fits into the slightly concave carboxy-terminal face of the contacting subunit. OmcS StructureThe OmcS monomer has . Alpha Helices, 310 Helices, Beta Strands , Loops . The structure assigned by the authors is 77% loops; Jmol objectively assigns 82% loops. The authors assigned 10% alpha helices, 7% 310 helices, and 6% beta strands. The OmcS structure determined by Filman et al. was very similar, with 80% loops assigned by the authors (86% by Jmol), having only 3% beta strand but otherwise very similar. We compared OmcS with three other c-type multi-heme cytochrome crystal structures: 1ofw, 3ucp, and 3ov0 had 45%, 49%, and 60% loops respectively. HemesEach OmcS monomer : C O N Fe. The hemes are arranged in parallel-displaced pairs. Each pair is orthogonal to the next pair. The , which likely contributes to the stability of the filament. More importantly, this produces a . This continuous chain of hemes is believed to be the basis of the electrical conductivity. Cysteine AnchorsEach heme is , which form thioether bonds with the heme vinyl groups (opposite the heme carboxyls). C O N S Fe. 12 CxxCH motifs in the OmcS sequence anchor the 6 hemes within each OmcS chain.
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See AlsoSee Also
- Malvankar: A list of all interactive 3D complements for publications from the Malvankar group.
Notes & ReferencesNotes & References
- ↑ 1.0 1.1 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. Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers. Cell. 2019 Apr 4;177(2):361-369.e10. doi: 10.1016/j.cell.2019.03.029. PMID:30951668 doi:http://dx.doi.org/10.1016/j.cell.2019.03.029
- ↑ Filman DJ, Marino SF, Ward JE, Yang L, Mester Z, Bullitt E, Lovley DR, Strauss M. Cryo-EM reveals the structural basis of long-range electron transport in a cytochrome-based bacterial nanowire. Commun Biol. 2019 Jun 19;2(1):219. doi: 10.1038/s42003-019-0448-9. PMID:31925024 doi:http://dx.doi.org/10.1038/s42003-019-0448-9