6N7V

Structure of bacteriophage T7 gp4 (helicase-primase, E343Q mutant) in complex with ssDNA, dTTP, AC dinucleotide, and CTP (from multiple lead complexes)

Summary for 6N7V

• Entry DOI: 10.2210/pdb6n7v/pdb
• EMDB information: 0357 0359 0362 0363 0364 0365
• Descriptor: DNA primase/helicase, DNA (93-MER), THYMIDINE-5'-TRIPHOSPHATE, ... (4 entities in total)
• Functional Keywords: helicase, atpase, dna polymerase, hexamer, dna replication, replisome, hydrolase, transferase-dna complex, transferase/dna
• Biological source: Enterobacteria phage T7; More
• Total number of polymer chains: 7
• Total formula weight: 402217.79

Authors

Gao, Y.,Fox, T.,Val, N.,Yang, W. (deposition date: 2018-11-28, release date: 2019-03-06, Last modification date: 2024-03-20)

Primary citation

Gao, Y.,Cui, Y.,Fox, T.,Lin, S.,Wang, H.,de Val, N.,Zhou, Z.H.,Yang, W.
Structures and operating principles of the replisome.
Science, 363:-, 2019

PubMed Abstract: 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.

PubMed: 30679383
DOI: 10.1126/science.aav7003

Experimental method

ELECTRON MICROSCOPY (3.8 Å)