7MR1
Cryo-EM structure of RecBCD with undocked RecBNuc and flexible RecD C-terminus
Summary for 7MR1
| Entry DOI | 10.2210/pdb7mr1/pdb |
| EMDB information | 23953 |
| Descriptor | RecBCD enzyme subunit RecB, RecBCD enzyme subunit RecC, RecBCD enzyme subunit RecD (3 entities in total) |
| Functional Keywords | sf1 helicase, complex, dna repair, motor protein, hydrolase |
| Biological source | Escherichia coli K12 More |
| Total number of polymer chains | 3 |
| Total formula weight | 330075.11 |
| Authors | Hao, L.,Zhang, R.,Lohman, T.M. (deposition date: 2021-05-07, release date: 2021-07-28, Last modification date: 2024-05-29) |
| Primary citation | Hao, L.,Zhang, R.,Lohman, T.M. Heterogeneity in E. coli RecBCD Helicase-DNA Binding and Base Pair Melting. J.Mol.Biol., 433:167147-167147, 2021 Cited by PubMed Abstract: E. coli RecBCD, a helicase/nuclease involved in double stranded (ds) DNA break repair, binds to a dsDNA end and melts out several DNA base pairs (bp) using only its binding free energy. We examined RecBCD-DNA initiation complexes using thermodynamic and structural approaches. Measurements of enthalpy changes for RecBCD binding to DNA ends possessing pre-melted ssDNA tails of increasing length suggest that RecBCD interacts with ssDNA as long as 17-18 nucleotides and can melt at least 10-11 bp upon binding a blunt DNA end. Cryo-EM structures of RecBCD alone and in complex with a blunt-ended dsDNA show significant conformational heterogeneities associated with the RecB nuclease domain (RecB) and the RecD subunit. In the absence of DNA, 56% of RecBCD molecules show no density for the RecB nuclease domain, RecB, and all RecBCD molecules show only partial density for RecD. DNA binding reduces these conformational heterogeneities, with 63% of the molecules showing density for both RecD and RecB. This suggests that the RecB domain is dynamic and influenced by DNA binding. The major RecBCD-DNA structural class in which RecB is docked onto RecC shows melting of at least 11 bp from a blunt DNA end, much larger than previously observed. A second structural class in which RecB is not docked shows only four bp melted suggesting that RecBCD complexes transition between states with different extents of DNA melting and that the extent of melting regulates initiation of helicase activity. PubMed: 34246654DOI: 10.1016/j.jmb.2021.167147 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (4.2 Å) |
Structure validation
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