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- EMDB-71670: Structure of the two-pore domain, outwardly rectifying potassium ... -

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Basic information

Entry
Database: EMDB / ID: EMD-71670
TitleStructure of the two-pore domain, outwardly rectifying potassium (TOK1) from Candida albicans, overall structure
Map dataCandida albicans TOK1, overall cryo-EM map, sharpening B factor -30
Sample
  • Complex: Candida albicans two-pore domain, outward rectifying potassium channel 1 (TOK1)
    • Protein or peptide: TOK potassium channel
  • Ligand: POTASSIUM ION
  • Ligand: DODECYL-BETA-D-MALTOSIDE
Keywordspotassium ion channel / METAL TRANSPORT
Function / homologystabilization of membrane potential / potassium ion leak channel activity / Two pore domain potassium channel / outward rectifier potassium channel activity / Potassium channel domain / Ion channel / plasma membrane / TOK potassium channel
Function and homology information
Biological speciesCandida albicans (yeast)
Methodsingle particle reconstruction / cryo EM / Resolution: 2.62 Å
AuthorsDurocher B / Manville RW / Yan R / Yu Z / Abbott GW / Miller AN
Funding support1 items
OrganizationGrant numberCountry
Not funded
CitationJournal: Nat Commun / Year: 2026
Title: Molecular architecture of the fungal-specific potassium channel TOK1.
Authors: Brice Durocher / Rían W Manville / Rui Yan / Zhiheng Yu / Geoffrey W Abbott / Alexandria N Miller /
Abstract: In Candida albicans, potassium (K) channels fine-tune ionic balance under stress, contributing to host colonization. Fungal two-pore domain, outwardly rectifying potassium (TOK) channels remain ...In Candida albicans, potassium (K) channels fine-tune ionic balance under stress, contributing to host colonization. Fungal two-pore domain, outwardly rectifying potassium (TOK) channels remain insufficiently characterized despite evidence implicating them in growth and viability. Here, we describe the atomic-resolution structure of a fungal potassium channel, TOK1 from C. albicans (CaTOK), revealing an architecture defined by eight transmembrane helices and a membrane topology distinct from previously characterized K⁺ channel classes. The first four helices form a tetraspanin-like bundle resembling auxiliary subunits of human neuronal ion channels. The pore features an inner helical gating movement analogous to mammalian dimeric K channels, while the K selectivity filter exhibits atypical ion coordination. A cytosolic C-terminal bundle forms an intramolecular network that likely stabilizes CaTOK and may mediate gating. These findings provide a framework for understanding TOK channel function and facilitate future studies of fungal ion homeostasis, pathogenicity, and therapeutic development.
History
DepositionJul 10, 2025-
Header (metadata) releaseApr 29, 2026-
Map releaseApr 29, 2026-
UpdateMay 13, 2026-
Current statusMay 13, 2026Processing site: RCSB / Status: Released

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Structure visualization

Supplemental images

emd_71670.png

Downloads & links

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Map

FileDownload / File: emd_71670.map.gz / Format: CCP4 / Size: 125 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
AnnotationCandida albicans TOK1, overall cryo-EM map, sharpening B factor -30
Projections & slices

Image control

Size
Brightness
Contrast
Others
AxesZ (Sec.)Y (Row.)X (Col.)
0.83 Å/pix.
x 320 pix.
= 264.64 Å		0.83 Å/pix.
x 320 pix.
= 264.64 Å		0.83 Å/pix.
x 320 pix.
= 264.64 Å

Surface

Projections

Slices (1/3)

Slices (1/2)

Slices (2/3)

Images are generated by Spider.

Voxel sizeX=Y=Z: 0.827 Å
Density

Histogram

Histogram (log scale)
Contour LevelBy AUTHOR: 0.3
Minimum - Maximum-0.6180227 - 1.5912011
Average (Standard dev.)0.005480019 (±0.04748352)
SymmetrySpace group: 1
Details

EMDB XML:

Map geometry
Axis orderXYZ
Origin000
Dimensions320320320
Spacing320320320
CellA=B=C: 264.64 Å
α=β=γ: 90.0 °

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Supplemental data

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Additional map: Candida albicans TOK1, overall cryo-EM map, unsharpened

Fileemd_71670_additional_1.map
AnnotationCandida albicans TOK1, overall cryo-EM map, unsharpened
Projections & Slices
AxesZYX

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Slices (1/2)
Density Histograms

Histogram

Histogram (log scale)

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Half map: Candida albicans TOK1, overall cryo-EM map, half map A

Fileemd_71670_half_map_1.map
AnnotationCandida albicans TOK1, overall cryo-EM map, half map A
Projections & Slices
AxesZYX

Projections

Slices (1/2)
Density Histograms

Histogram

Histogram (log scale)

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Half map: Candida albicans TOK1, overall cryo-EM map, half map B

Fileemd_71670_half_map_2.map
AnnotationCandida albicans TOK1, overall cryo-EM map, half map B
Projections & Slices
AxesZYX

Projections

Slices (1/2)
Density Histograms

Histogram

Histogram (log scale)

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Sample components

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Entire : Candida albicans two-pore domain, outward rectifying potassium ch...

EntireName: Candida albicans two-pore domain, outward rectifying potassium channel 1 (TOK1)
Components
  • Complex: Candida albicans two-pore domain, outward rectifying potassium channel 1 (TOK1)
    • Protein or peptide: TOK potassium channel
  • Ligand: POTASSIUM ION
  • Ligand: DODECYL-BETA-D-MALTOSIDE

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Supramolecule #1: Candida albicans two-pore domain, outward rectifying potassium ch...

SupramoleculeName: Candida albicans two-pore domain, outward rectifying potassium channel 1 (TOK1)
type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1
Source (natural)Organism: Candida albicans (yeast)

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Macromolecule #1: TOK potassium channel

MacromoleculeName: TOK potassium channel / type: protein_or_peptide / ID: 1 / Details: C-terminal HRV 3C Twin strep tag / Number of copies: 2 / Enantiomer: LEVO
Source (natural)Organism: Candida albicans (yeast)
Molecular weightTheoretical: 88.76057 KDa
Recombinant expressionOrganism: Spodoptera frugiperda (fall armyworm)
SequenceString: MGFHAPLNGS SKNSKSSAFA SFDSASVMQI VNKAKDKIVP DAQFHQTITD QGIRHYQEKL SPLLQNSYHG ANVNTNKQDS SPMKSPVTL QHALNVRLES ILSLNVRPGE PFFVLWFLIS SYFPLIAACL GPLANMISIV ALVEHWKVDI ITRKNVPDIP K VVVMNAVS ...String:
MGFHAPLNGS SKNSKSSAFA SFDSASVMQI VNKAKDKIVP DAQFHQTITD QGIRHYQEKL SPLLQNSYHG ANVNTNKQDS SPMKSPVTL QHALNVRLES ILSLNVRPGE PFFVLWFLIS SYFPLIAACL GPLANMISIV ALVEHWKVDI ITRKNVPDIP K VVVMNAVS LALGLIGNIS LLMNFSRSVK YLVSQSVSII AWLCASALLA AALFVTNREF GGENPKYVPS EGFYFAAFTS GN YFVCMLI LVINFMGYSL KKYPPTFNLD QRQRTLMLFT ILFSTWTVIG AFTMGSLIDD ISYGSALYYC IVSFLTIGLG DIL PETSGA KVAVLVFSLG GVLIMGLIVA TLRSVILSSA APAIFWNDVE KTRIALLAQL DKENRHLTSE ESFHEMRVLR RKVK SRHKK VSLALTIAVF MIFWLIGALI FQKIEKWSYF NAMYFCFLCL ITIGYGDYAP KTSLGRVFFV SWAVGAVPLM TILVS NVGD TLYEISNDIS AWFSTWMFST KEEYRDLKWK KKKLQEDQED QLTVNSEAVR SSELDEDLDL AKMEQEASLE ARDNSS NGE IGAASIDNPN EDVKVEDNDT CITNSSNSNM RKDQENNSYS ERSVCKSEKQ NFDIERIRQK IASKKQVHEM LIDYLEK MK PLIGDSIESP NRKYSYKQWK GAYDGFWLSE SSPLRLPLKE PNYLILKIYF EIEMMLRGLV DMEIEDLKTL TIQDVSNE L SSSSSTDIKF ARTIKFDDDK VDGLEVLFQG PTAAAVGSGG LEGGGGWSHP QFEKGGGSGG GSGGGSWSHP QFEK

UniProtKB: TOK potassium channel

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Macromolecule #2: POTASSIUM ION

MacromoleculeName: POTASSIUM ION / type: ligand / ID: 2 / Number of copies: 3 / Formula: K
Molecular weightTheoretical: 39.098 Da

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Macromolecule #3: DODECYL-BETA-D-MALTOSIDE

MacromoleculeName: DODECYL-BETA-D-MALTOSIDE / type: ligand / ID: 3 / Number of copies: 46 / Formula: LMT
Molecular weightTheoretical: 510.615 Da
Chemical component information

ChemComp-LMT:
DODECYL-BETA-D-MALTOSIDE / detergent*YM

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Experimental details

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Structure determination

Methodcryo EM
Processingsingle particle reconstruction
Aggregation stateparticle

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Sample preparation

BufferpH: 7
VitrificationCryogen name: ETHANE

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Electron microscopy

MicroscopeTFS KRIOS
Image recordingFilm or detector model: GATAN K3 (6k x 4k) / Average electron dose: 50.0 e/Å2
Electron beamAcceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
Electron opticsIllumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 2.0 µm / Nominal defocus min: 0.8 µm
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company

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Image processing

CTF correctionType: NONE
Startup modelType of model: NONE
Final reconstructionResolution.type: BY AUTHOR / Resolution: 2.62 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: cryoSPARC / Number images used: 378494
Initial angle assignmentType: MAXIMUM LIKELIHOOD
Final angle assignmentType: MAXIMUM LIKELIHOOD

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