8DUO

DNA-free T4 Bacteriophage gp41 hexamer

Summary for 8DUO

• Entry DOI: 10.2210/pdb8duo/pdb
• EMDB information: 27724
• Descriptor: DnaB-like replicative helicase, PHOSPHOTHIOPHOSPHORIC ACID-ADENYLATE ESTER, MAGNESIUM ION (3 entities in total)
• Functional Keywords: phage, complex, helicase, replication-dna-rna complex, replication/dna/rna
• Biological source: Escherichia phage T4
• Total number of polymer chains: 6
• Total formula weight: 324714.85

Authors

Feng, X.,Li, H. (deposition date: 2022-07-27, release date: 2023-06-14, Last modification date: 2023-08-23)

Primary citation

Feng, X.,Spiering, M.M.,de Luna Almeida Santos, R.,Benkovic, S.J.,Li, H.
Structural basis of the T4 bacteriophage primosome assembly and primer synthesis.
Nat Commun, 14:4396-4396, 2023

PubMed Abstract: The T4 bacteriophage gp41 helicase and gp61 primase assemble into a primosome to couple DNA unwinding with RNA primer synthesis for DNA replication. How the primosome is assembled and how the primer length is defined are unclear. Here we report a series of cryo-EM structures of T4 primosome assembly intermediates. We show that gp41 alone is an open spiral, and ssDNA binding triggers a large-scale scissor-like conformational change that drives the ring closure and activates the helicase. Helicase activation exposes a cryptic hydrophobic surface to recruit the gp61 primase. The primase binds the helicase in a bipartite mode in which the N-terminal Zn-binding domain and the C-terminal RNA polymerase domain each contain a helicase-interacting motif that bind to separate gp41 N-terminal hairpin dimers, leading to the assembly of one primase on the helicase hexamer. Our study reveals the T4 primosome assembly process and sheds light on the RNA primer synthesis mechanism.

PubMed: 37474605
DOI: 10.1038/s41467-023-40106-2

Experimental method

ELECTRON MICROSCOPY (5.7 Å)