|Entry||Database: EMDB / ID: 3887|
|Title||AcrB in a SMALP|
|Map data||AcrB in SMA polymer. Map filtered by local resolution in RELION 2.1|
|Sample||Escherichia coli multidrug efflux transporter AcrB in a SMALP platform:|
|Source||Escherichia coli (E. coli)|
|Method||single particle reconstruction / cryo EM / 8.8 Å resolution|
|Authors||Parmar M / Rawson S / Scarff CA / Goldman A / Dafforn TR / Muench SP / Postis VLG|
|Citation||Journal: Biochim. Biophys. Acta / Year: 2018|
Title: Using a SMALP platform to determine a sub-nm single particle cryo-EM membrane protein structure.
Authors: Mayuriben Parmar / Shaun Rawson / Charlotte A Scarff / Adrian Goldman / Timothy R Dafforn / Stephen P Muench / Vincent L G Postis
Abstract: The field of membrane protein structural biology has been revolutionized over the last few years with a number of high profile structures being solved using cryo-EM including Piezo, Ryanodine ...The field of membrane protein structural biology has been revolutionized over the last few years with a number of high profile structures being solved using cryo-EM including Piezo, Ryanodine receptor, TRPV1 and the Glutamate receptor. Further developments in the EM field hold the promise of even greater progress in terms of greater resolution, which for membrane proteins is still typically within the 4-7Å range. One advantage of a cryo-EM approach is the ability to study membrane proteins in more "native" like environments for example proteoliposomes, amphipols and nanodiscs. Recently, styrene maleic acid co-polymers (SMA) have been used to extract membrane proteins surrounded by native lipids (SMALPs) maintaining a more natural environment. We report here the structure of the Escherichia coli multidrug efflux transporter AcrB in a SMALP scaffold to sub-nm resolution, with the resulting map being consistent with high resolution crystal structures and other EM derived maps. However, both the C-terminal helix (TM12) and TM7 are poorly defined in the map. These helices are at the exterior of the helical bundle and form the greater interaction with the native lipids and SMA polymer and may represent a more dynamic region of the protein. This work shows the promise of using an SMA approach for single particle cryo-EM studies to provide sub-nm structures.
|Date||Deposition: Sep 28, 2017 / Header (metadata) release: Oct 25, 2017 / Map release: Oct 25, 2017 / Last update: Dec 6, 2017|
|Structure viewer||EM map: |
Downloads & links
|File||emd_3887.map.gz (map file in CCP4 format, 8389 KB)|
|Projections & slices|
Images are generated by Spider.
|Voxel size||X=Y=Z: 2.13 Å|
CCP4 map header:
-Entire Escherichia coli multidrug efflux transporter AcrB in a SMALP platform
|Entire||Name: Escherichia coli multidrug efflux transporter AcrB in a SMALP platform|
Number of components: 1
|Mass||Theoretical: 340 kDa|
-Component #1: protein, Escherichia coli multidrug efflux transporter AcrB in a ...
|Protein||Name: Escherichia coli multidrug efflux transporter AcrB in a SMALP platform|
Recombinant expression: No
|Mass||Theoretical: 340 kDa|
|Source||Species: Escherichia coli (E. coli)|
|Source (engineered)||Expression System: Escherichia coli (E. coli) / Strain: C43(DE3)|
|Specimen||Specimen state: particle / Method: cryo EM|
|Sample solution||Specimen conc.: 1 mg/ml / pH: 8|
|Vitrification||Cryogen name: ETHANE|
-Electron microscopy imaging
Model: Titan Krios / Image courtesy: FEI Company
|Imaging||Microscope: FEI TITAN KRIOS|
|Electron gun||Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Electron dose: 70 e/Å2 / Illumination mode: FLOOD BEAM|
|Lens||Imaging mode: BRIGHT FIELD|
|Specimen Holder||Model: OTHER|
|Processing||Method: single particle reconstruction / Applied symmetry: C3 (3 fold cyclic) / Number of projections: 26480|
|3D reconstruction||Resolution: 8.8 Å / Resolution method: FSC 0.143 CUT-OFF / Euler angles: RELION auto-refinement|
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