Biological Assembly 1  

Global Symmetry: Helical - H  (3D View)
Global Stoichiometry: Homo 4-mer - A4 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 199.28 kDa 
• Atom Count: 11,324 
• Modelled Residue Count: 1,336 
• Deposited Residue Count: 1,680 
• Unique protein chains: 1
• Unique nucleic acid chains: 1

 7YPO

Cryo-EM structure of baculovirus LEF-3 in complex with ssDNA

• PDB DOI: 10.2210/pdb7YPO/pdb
• EM Map EMD-34010: EMDB EMDataResource

• Classification: DNA BINDING PROTEIN
• Organism(s): Helicoverpa armigera nucleopolyhedrovirus, synthetic construct
• Expression System: Escherichia coli BL21
• Mutation(s): No 


• Deposited: 2022-08-04 Released: 2023-01-25 
• Deposition Author(s): Yin, J., Fu, Y., Rao, G., Li, Z., Cao, S.
• Funding Organization(s): Ministry of Science and Technology (MoST, China)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.50 Å
• Aggregation State: HELICAL ARRAY 
• Reconstruction Method: HELICAL 

Literature

Structural transitions during the cooperative assembly of baculovirus single-stranded DNA-binding protein on ssDNA.

Yin, J., Fu, Y., Rao, G., Li, Z., Tian, K., Chong, T., Kuang, K., Wang, M., Hu, Z., Cao, S.

(2022) Nucleic Acids Res 50: 13100-13113

• PubMed: 36477586 
• DOI: 10.1093/nar/gkac1142
• Primary Citation of Related Structures:  
  7YNY, 7YPO, 7YPQ


• PubMed Abstract: 
  

Single-stranded DNA-binding proteins (SSBs) interact with single-stranded DNA (ssDNA) to form filamentous structures with various degrees of cooperativity, as a result of intermolecular interactions between neighboring SSB subunits on ssDNA. However, it is still challenging to perform structural studies on SSB-ssDNA filaments at high resolution using the most studied SSB models, largely due to the intrinsic flexibility of these nucleoprotein complexes. In this study, HaLEF-3, an SSB protein from Helicoverpa armigera nucleopolyhedrovirus, was used for in vitro assembly of SSB-ssDNA filaments, which were structurally studied at atomic resolution using cryo-electron microscopy. Combined with the crystal structure of ssDNA-free HaLEF-3 octamers, our results revealed that the three-dimensional rearrangement of HaLEF-3 induced by an internal hinge-bending movement is essential for the formation of helical SSB-ssDNA complexes, while the contacting interface between adjacent HaLEF-3 subunits remains basically intact. We proposed a local cooperative SSB-ssDNA binding model, in which, triggered by exposure to oligonucleotides, HaLEF-3 molecules undergo ring-to-helix transition to initiate continuous SSB-SSB interactions along ssDNA. Unique structural features revealed by the assembly of HaLEF-3 on ssDNA suggest that HaLEF-3 may represent a new class of SSB.

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Organizational Affiliation: 

CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, PR China.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Lef3	A, B, C, D	413	Helicoverpa armigera nucleopolyhedrovirus	Mutation(s): 0
UniProt
Find proteins for Q91BW6 (Helicoverpa armigera nucleopolyhedrovirus) Explore Q91BW6  Go to UniProtKB:  Q91BW6

Entity ID: 2
Molecule	Chains	Length	Organism	Image
DNA (28-MER)	E [auth Q]	28	synthetic construct

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.50 Å
• Aggregation State: HELICAL ARRAY 
• Reconstruction Method: HELICAL 

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2023-01-25 
Deposition Author(s): Yin, J., Fu, Y., Rao, G., Li, Z., Cao, S.

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Funding Organization	Location	Grant Number
Ministry of Science and Technology (MoST, China)	China	2018YFA0507200

Revision History  

• Version 1.0: 2023-01-25
  Type: Initial release