User:Nikhil Malvankar/Cytochrome nanowires

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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

1 Structure Tour
2 Download
- 2.1 Animations for Powerpoint
3 See Also
4 Notes & References

Structure Tour

1 Background
2 Nanowire Structure
3 OmcS Structure
4 Hemes
- 4.1 Cysteine Anchors

Background

The 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 Structure

A 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 .

Amino Terminus

Carboxy Terminus

The amino terminus forms a bulge that fits into the slightly concave carboxy-terminal face of the contacting subunit.

OmcS Structure

The 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.

Hemes

Each 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 Anchors

Each 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.

Download

Animations for Powerpoint

Click images to see them full size, or to download them.

Notes & 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

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Eric Martz

Retrieved from "http://52.214.119.220/wiki/index.php/User:Nikhil_Malvankar/Cytochrome_nanowires"

@@ Line 63: / Line 63: @@
 ====Cysteine Anchors====
-Each heme is covalently anchored to two cysteines, which form thioether bonds with the heme vinyl groups (opposite the heme carboxyls). 12 CxxCH motifs in the [https://www.uniprot.org/uniprot/Q74A86#sequences OmcS sequence] anchor the 6 hemes within each OmcS chain.
+Each heme is <scene name='83/835223/Heme_cysteine/1'>covalently anchored to two cysteines</scene>, which form thioether bonds with the heme vinyl groups (opposite the heme carboxyls).
+{{Template:ColorKey_Element_C}}
+{{Template:ColorKey_Element_O}}
+{{Template:ColorKey_Element_N}}
+{{Template:ColorKey_Element_S}}
+{{Template:ColorKey_Element_Fe}}.
+CxxCH motifs in the [https://www.uniprot.org/uniprot/Q74A86#sequences OmcS sequence] anchor the 6 hemes within each OmcS chain.

User:Nikhil Malvankar/Cytochrome nanowires

From Proteopedia

Revision as of 21:53, 13 February 2020

Contents

Structure Tour

Contents

Background

Nanowire Structure

OmcS Structure

Hemes

Cysteine Anchors

Download

Animations for Powerpoint

See Also

Notes & References

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