6N7V image
Entry Detail
PDB ID:
6N7V
EMDB ID:
Title:
Structure of bacteriophage T7 gp4 (helicase-primase, E343Q mutant) in complex with ssDNA, dTTP, AC dinucleotide, and CTP (from multiple lead complexes)
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2018-11-28
Release Date:
2019-03-06
Method Details:
Experimental Method:
Resolution:
3.80 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:DNA primase/helicase
Mutations:E343Q
Chain IDs:A, B, C, D, E, F
Chain Length:566
Number of Molecules:6
Biological Source:Enterobacteria phage T7
Polymer Type:polydeoxyribonucleotide
Description:DNA (93-MER)
Chain IDs:G (auth: T)
Chain Length:76
Number of Molecules:1
Biological Source:Enterobacteria phage T7
Primary Citation
Structures and operating principles of the replisome.
Science 363 ? ? (2019)
PMID: 30679383 DOI: 10.1126/science.aav7003

Abstact

Visualization in atomic detail of the replisome that performs concerted leading- and lagging-DNA strand synthesis at a replication fork has not been reported. Using bacteriophage T7 as a model system, we determined cryo-electron microscopy structures up to 3.2-angstroms resolution of helicase translocating along DNA and of helicase-polymerase-primase complexes engaging in synthesis of both DNA strands. Each domain of the spiral-shaped hexameric helicase translocates sequentially hand-over-hand along a single-stranded DNA coil, akin to the way AAA+ ATPases (adenosine triphosphatases) unfold peptides. Two lagging-strand polymerases are attached to the primase, ready for Okazaki fragment synthesis in tandem. A β hairpin from the leading-strand polymerase separates two parental DNA strands into a T-shaped fork, thus enabling the closely coupled helicase to advance perpendicular to the downstream DNA duplex. These structures reveal the molecular organization and operating principles of a replisome.

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Primary Citation of related structures