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- PDB-6j6k: Apo-state streptavidin -

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Database: PDB / ID: 6j6k
TitleApo-state streptavidin
KeywordsCYTOSOLIC PROTEIN / streptavidin
Function / homologyAvidin/streptavidin / Avidin / Avidin-like, conserved site / Avidin-like superfamily / Avidin family / Avidin-like domain signature. / Avidin-like domain profile. / extracellular region / Streptavidin
Function and homology information
Biological speciesStreptomyces avidinii (bacteria)
MethodELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.3 Å
AuthorsFan, X. / Wang, J. / Lei, J.L. / Wang, H.W.
Funding supportChina , 1件
OrganizationGrant numberCountry
Ministry of Science and Technology (China)2016YFA0501100 to H.W.China
CitationJournal: Nat Commun / Year: 2019
Title: Single particle cryo-EM reconstruction of 52 kDa streptavidin at 3.2 Angstrom resolution.
Authors: Xiao Fan / Jia Wang / Xing Zhang / Zi Yang / Jin-Can Zhang / Lingyun Zhao / Hai-Lin Peng / Jianlin Lei / Hong-Wei Wang /
Abstract: The fast development of single-particle cryogenic electron microscopy (cryo-EM) has made it more feasible to obtain the 3D structure of well-behaved macromolecules with a molecular weight higher than ...The fast development of single-particle cryogenic electron microscopy (cryo-EM) has made it more feasible to obtain the 3D structure of well-behaved macromolecules with a molecular weight higher than 300 kDa at ~3 Å resolution. However, it remains a challenge to obtain the high-resolution structures of molecules smaller than 200 kDa using single-particle cryo-EM. In this work, we apply the Cs-corrector-VPP-coupled cryo-EM to study the 52 kDa streptavidin (SA) protein supported on a thin layer of graphene and embedded in vitreous ice. We are able to solve both the apo-SA and biotin-bound SA structures at near-atomic resolution using single-particle cryo-EM. We demonstrate that the method has the potential to determine the structures of molecules as small as 39 kDa.
Validation Report
SummaryFull reportAbout validation report
DateDeposition: Jan 15, 2019 / Release: May 29, 2019
RevisionDateData content typeGroupCategoryItemProviderType
1.0May 29, 2019Structure modelrepositoryInitial release
1.1Jun 19, 2019Structure modelData collection / Database referencescitation / citation_author_citation.journal_volume / _citation.page_first / _citation.page_last / _citation.pdbx_database_id_PubMed / _citation.title / _citation_author.name

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Deposited unit
A: Streptavidin
B: Streptavidin
C: Streptavidin
D: Streptavidin

Theoretical massNumber of molelcules
Total (without water)50,3874

TypeNameSymmetry operationNumber
identity operation1_5551
Buried area8250 Å2
ΔGint-56 kcal/mol
Surface area20640 Å2


#1: Protein/peptide
Streptavidin /

Mass: 12596.641 Da / Num. of mol.: 4 / Source method: isolated from a natural source / Source: (natural) Streptomyces avidinii (bacteria) / References: UniProt: P22629

Experimental details


EM experimentAggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction

Sample preparation

ComponentName: Streptavidin / Type: COMPLEX / Entity ID: 1 / Source: NATURAL
Molecular weightValue: 0.052 MDa / Experimental value: YES
Source (natural)Organism: Streptomyces avidinii (bacteria)
Buffer solutionpH: 7.5
Buffer component

Buffer-ID: 1

125 mMTris-HClTris(HOCH2)3CNH2
275 mMSodium chlorideNaClSodium chloride
SpecimenConc.: 0.2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES
VitrificationInstrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 285 K

Electron microscopy imaging

Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
MicroscopyModel: FEI TITAN KRIOS
Electron gunElectron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM
Electron lensMode: BRIGHT FIELDBright-field microscopy / Nominal magnification: 215000 X / Nominal defocus max: -800 nm / Nominal defocus min: -800 nm / Cs: 0.01 mm / C2 aperture diameter: 50 µns / Alignment procedure: ZEMLIN TABLEAU
Image recordingAverage exposure time: 2.56 sec. / Electron dose: 50 e/Å2 / Detector mode: SUPER-RESOLUTION / Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Num. of grids imaged: 1 / Num. of real images: 1450
EM imaging opticsPhase plate: Using volta phase plate
Spherical aberration corrector: Using spherical aberration corrector
Image scansSampling size: 5 µns / Width: 3838 / Height: 3710 / Movie frames/image: 32 / Used frames/image: 1-32


SoftwareName: PHENIX / Version: 1.12_2829: / Classification: refinement
EM software
1Gautomatchparticle selection
4RELIONCTF correction
10RELIONinitial Euler assignment
11RELIONfinal Euler assignment
13RELION3D reconstruction
Particle selectionNum. of particles selected: 709967
SymmetryPoint symmetry: D2 (2x2 fold dihedral)
3D reconstructionResolution: 3.3 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 23991 / Num. of class averages: 1 / Symmetry type: POINT
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