4M4W

Mechanistic implications for the bacterial primosome assembly of the structure of a helicase-helicase loader complex

Summary for 4M4W

• Entry DOI: 10.2210/pdb4m4w/pdb
• Descriptor: Replicative helicase, DNA primase, Primosomal protein DnaI (3 entities in total)
• Functional Keywords: primase, helicase loader, dnab, dnag, dnai, dna replication, replication
• Biological source: Geobacillus stearothermophilus; More
• Total number of polymer chains: 15
• Total formula weight: 576533.05

Authors

Liu, B.,Eliason, W.K.,Steitz, T.A. (deposition date: 2013-08-07, release date: 2013-09-25, Last modification date: 2013-10-02)

Primary citation

Liu, B.,Eliason, W.K.,Steitz, T.A.
Structure of a helicase-helicase loader complex reveals insights into the mechanism of bacterial primosome assembly.
Nat Commun, 4:2495-2495, 2013

PubMed Abstract: During the assembly of the bacterial loader-dependent primosome, helicase loader proteins bind to the hexameric helicase ring, deliver it onto the oriC DNA and then dissociate from the complex. Here, to provide a better understanding of this key process, we report the crystal structure of the ~570-kDa prepriming complex between the Bacillus subtilis loader protein and the Bacillus stearothermophilus helicase, as well as the helicase-binding domain of primase with a molar ratio of 6:6:3 at 7.5 Å resolution. The overall architecture of the complex exhibits a three-layered ring conformation. Moreover, the structure combined with the proposed model suggests that the shift from the 'open-ring' to the 'open-spiral' and then the 'closed-spiral' state of the helicase ring due to the binding of single-stranded DNA may be the cause of the loader release.

PubMed: 24048025
DOI: 10.1038/ncomms3495

Experimental method

X-RAY DIFFRACTION (6.1 Å)