National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)
R01-AI103171
United States
Citation
Journal: Nature / Year: 2018 Title: Cryo-EM structure of the insect olfactory receptor Orco. Authors: Joel A Butterwick / Josefina Del Mármol / Kelly H Kim / Martha A Kahlson / Jackson A Rogow / Thomas Walz / Vanessa Ruta / Abstract: The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a family of odorant-gated ion ...The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a family of odorant-gated ion channels comprised of a highly conserved co-receptor (Orco) and a divergent odorant receptor (OR) that confers chemical specificity. Here, we present the single-particle cryo-electron microscopy structure of an Orco homomer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution, providing structural insight into this receptor family. Orco possesses a novel channel architecture, with four subunits symmetrically arranged around a central pore that diverges into four lateral conduits that open to the cytosol. The Orco tetramer has few inter-subunit interactions within the membrane and is bound together by a small cytoplasmic anchor domain. The minimal sequence conservation among ORs maps largely to the pore and anchor domain, shedding light on how the architecture of this receptor family accommodates its remarkable sequence diversity and facilitates the evolution of odour tuning.
Mass: 53513.238 Da / Num. of mol.: 4 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Apocrypta bakeri (insect) / Gene: Or2 / Production host: Homo sapiens (human) / References: UniProt: B0FAQ4
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Experimental details
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Experiment
Experiment
Method: ELECTRON MICROSCOPY
EM experiment
Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction
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Sample preparation
Component
Name: Orco homotetramer bound to four Fab molecules in a detergent micelle Type: COMPLEX / Entity ID: all / Source: RECOMBINANT
Molecular weight
Experimental value: NO
Source (natural)
Organism: Apocrypta bakeri (insect)
Source (recombinant)
Organism: Homo sapiens (human)
Buffer solution
pH: 7.5
Specimen
Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES
Vitrification
Cryogen name: ETHANE
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Electron microscopy imaging
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
Microscopy
Model: FEI TITAN KRIOS
Electron gun
Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM
Electron lens
Mode: BRIGHT FIELD
Image recording
Average exposure time: 0.2 sec. / Electron dose: 80 e/Å2 / Detector mode: SUPER-RESOLUTION / Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Num. of grids imaged: 1221 / Num. of real images: 53141
Image scans
Movie frames/image: 50 / Used frames/image: 1-50
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Processing
Software
Name
Version
Classification
NB
PHENIX
1.13_2998:
refinement
PDB_EXTRACT
3.22
dataextraction
CTF correction
Type: PHASE FLIPPING AND AMPLITUDE CORRECTION
3D reconstruction
Resolution: 3.5 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 53141 / Symmetry type: POINT
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