6qem

E. coli DnaBC complex bound to ssDNA

Loading... Status: waiting for Mol* initialization Structural highlights 6qem is a 13 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.4Å Ligands: 08T, ADP, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DNAB_ECOLI Participates in initiation and elongation during chromosome replication; it exhibits DNA-dependent ATPase activity and contains distinct active sites for ATP binding, DNA binding, and interaction with DnaC protein, primase, and other prepriming proteins. Publication Abstract from PubMed In cells, dedicated AAA+ ATPases deposit hexameric, ring-shaped helicases onto DNA to initiate chromosomal replication. To better understand the mechanisms by which helicase loading can occur, we used cryo-EM to determine sub-4-A-resolution structures of the E. coli DnaBDnaC helicaseloader complex with nucleotide in pre- and post-DNA engagement states. In the absence of DNA, six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain, stabilizing this conformation through nucleotide-dependent ATPase interactions. Upon binding DNA, DnaC hydrolyzes ATP, allowing DnaB to isomerize into a topologically closed, pre-translocation state competent to bind primase. Our data show how DnaC opens the DnaB ring and represses the helicase prior to DNA binding and how DnaC ATPase activity is reciprocally regulated by DnaB and DNA. Comparative analyses reveal how the helicase loading mechanism of DnaC parallels and diverges from homologous AAA+ systems involved in DNA replication and transposition. Physical Basis for the Loading of a Bacterial Replicative Helicase onto DNA.,Arias-Palomo E, Puri N, O'Shea Murray VL, Yan Q, Berger JM Mol Cell. 2019 Feb 16. pii: S1097-2765(19)30043-7. doi:, 10.1016/j.molcel.2019.01.023. PMID:30797687 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DnaC helicase loader Helicase 3D structures

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