6N7S

Structure of bacteriophage T7 E343Q mutant gp4 helicase-primase in complex with ssDNA, dTTP, AC dinucleotide and CTP (form II)

Summary for 6N7S

• Entry DOI: 10.2210/pdb6n7s/pdb
• EMDB information: 0357 0359 0362 0363 0364 0365
• Descriptor: DNA primase/helicase, DNA (25-MER), THYMIDINE-5'-TRIPHOSPHATE, ... (4 entities in total)
• Functional Keywords: helicase, atpase, hexamer, dna replication, hydrolase, transferase-dna complex, transferase/dna
• Biological source: Enterobacteria phage T7; More
• Total number of polymer chains: 7
• Total formula weight: 386027.35

Authors

Gao, Y.,Cui, Y.,Zhou, Z.,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 (4.6 Å)