7YPO

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

Summary for 7YPO

• Entry DOI: 10.2210/pdb7ypo/pdb
• Related: 7YNY
• EMDB information: 34010
• Descriptor: Lef3, DNA (28-MER) (2 entities in total)
• Functional Keywords: ssdna, ssb, baculovirus, dna binding protein
• Biological source: Helicoverpa armigera nucleopolyhedrovirus; More
• Total number of polymer chains: 5
• Total formula weight: 199275.66

Authors

Yin, J.,Fu, Y.,Rao, G.,Li, Z.,Cao, S. (deposition date: 2022-08-04, release date: 2023-01-25, Last modification date: 2024-07-03)

Primary citation

Yin, J.,Fu, Y.,Rao, G.,Li, Z.,Tian, K.,Chong, T.,Kuang, K.,Wang, M.,Hu, Z.,Cao, S.
Structural transitions during the cooperative assembly of baculovirus single-stranded DNA-binding protein on ssDNA.
Nucleic Acids Res., 50:13100-13113, 2022

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.

PubMed: 36477586
DOI: 10.1093/nar/gkac1142

Experimental method

ELECTRON MICROSCOPY (3.5 Å)