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-Structure paper
Title | Structural transitions during the cooperative assembly of baculovirus single-stranded DNA-binding protein on ssDNA. |
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Journal, issue, pages | Nucleic Acids Res, Vol. 50, Issue 22, Page 13100-13113, Year 2022 |
Publish date | Dec 9, 2022 |
Authors | Jiayi Yin / Yan Fu / Guibo Rao / Zhiqiang Li / Kexing Tian / Tingting Chong / Kai Kuang / Manli Wang / Zhihong Hu / Sheng Cao / |
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 ...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. |
External links | Nucleic Acids Res / PubMed:36477586 / PubMed Central |
Methods | EM (helical sym.) / EM (single particle) / X-ray diffraction |
Resolution | 3.1 - 3.51 Å |
Structure data | EMDB-34010, PDB-7ypo: EMDB-34011, PDB-7ypq: PDB-7yny: |
Source |
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Keywords | DNA BINDING PROTEIN / ssDNA / SSB / Baculovirus / Replication |