6BBM

Mechanisms of Opening and Closing of the Bacterial Replicative Helicase: The DnaB Helicase and Lambda P Helicase Loader Complex

Summary for 6BBM

• Entry DOI: 10.2210/pdb6bbm/pdb
• EMDB information: 7076
• Descriptor: Replicative DNA helicase, Replication protein P, ADENOSINE-5'-DIPHOSPHATE (3 entities in total)
• Functional Keywords: helicase loader, helicase, dna replication, atpase, dna replication initiation, bacteriophage lambda, replication
• Biological source: Escherichia coli O111:NM; More
• Total number of polymer chains: 11
• Total formula weight: 432547.78

Authors

Chase, J.,Catalano, A.,Noble, A.J.,Eng, E.T.,Olinares, P.D.B.,Molloy, K.,Pakotiprapha, D.,Samuels, M.,Chain, B.,des Georges, A.,Jeruzalmi, D. (deposition date: 2017-10-18, release date: 2019-03-06, Last modification date: 2024-03-13)

Primary citation

Chase, J.,Catalano, A.,Noble, A.J.,Eng, E.T.,Olinares, P.D.,Molloy, K.,Pakotiprapha, D.,Samuels, M.,Chait, B.,des Georges, A.,Jeruzalmi, D.
Mechanisms of opening and closing of the bacterial replicative helicase.
Elife, 7:-, 2018

PubMed Abstract: Assembly of bacterial ring-shaped hexameric replicative helicases on single-stranded (ss) DNA requires specialized loading factors. However, mechanisms implemented by these factors during opening and closing of the helicase, which enable and restrict access to an internal chamber, are not known. Here, we investigate these mechanisms in the DnaB helicase•bacteriophage λ helicase loader (λP) complex. We show that five copies of λP bind at DnaB subunit interfaces and reconfigure the helicase into an open spiral conformation that is intermediate to previously observed closed ring and closed spiral forms; reconfiguration also produces openings large enough to admit ssDNA into the inner chamber. The helicase is also observed in a restrained inactive configuration that poises it to close on activating signal, and transition to the translocation state. Our findings provide insights into helicase opening, delivery to the origin and ssDNA entry, and closing in preparation for translocation.

PubMed: 30582519
DOI: 10.7554/eLife.41140

Experimental method

ELECTRON MICROSCOPY (4.1 Å)