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-Structure paper
タイトル | Physical Basis for the Loading of a Bacterial Replicative Helicase onto DNA. |
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ジャーナル・号・ページ | Mol Cell, Vol. 74, Issue 1, Page 173-184.e4, Year 2019 |
掲載日 | 2019年4月4日 |
著者 | Ernesto Arias-Palomo / Neha Puri / Valerie L O'Shea Murray / Qianyun Yan / James M Berger / |
PubMed 要旨 | 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 ...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-Å-resolution structures of the E. coli DnaB⋅DnaC helicase⋅loader 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. |
リンク | Mol Cell / PubMed:30797687 / PubMed Central |
手法 | EM (単粒子) |
解像度 | 3.4 - 3.9 Å |
構造データ | |
化合物 | ChemComp-ADP: ChemComp-MG: ChemComp-08T: |
由来 |
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キーワード | REPLICATION / Helicase / helicase loader / AAA+ / RecA |