DNA Replication Mechanisms in Bacteriophages

Bacteriophages deploy streamlined yet robust strategies to replicate their DNA within host cells. Replication typically initiates at defined viral origins recognised by phage-encoded initiator proteins, followed by recruitment of a minimal replisome composed of DNA polymerase, helicase, primase and auxiliary factors. In well characterised systems such as phage T7, a single bifunctional primase-helicase unwinds parental DNA and lays down RNA primers, while the polymerase extends nascent strands with high processivity. Alternative strategies include rolling-circle replication, strand displacement and recombination-dependent mechanisms, reflecting adaptation to diverse genome architectures. Host factors such as single-stranded DNA binding proteins and nucleotide exchange factors further enhance replication efficiency. Understanding these mechanisms elucidates fundamental principles of macromolecular coordination, informs biotechnological tool development and suggests novel avenues for antiviral agents and molecular engineering.

Research from Nature Portfolio

The minimal replication apparatus of bacteriophage T7 has been shown to tolerate DNA lesions directly without fork disassembly, revealing a permissive pathway for lesion bypass. When encountering cyclobutane pyrimidine dimers on the leading strand, the viral polymerase remains bound and synthesises through the lesion in concert with the helicase. Crucially, helicase-polymerase interactions stabilise the replisome at damaged sites, preventing uncoupling or recruitment of accessory repair proteins. This direct bypass mechanism underscores an intrinsic flexibility of phage replication machineries and suggests that specific inter-protein interfaces may serve as targets for antiviral modulation or the design of lesion-tolerant polymerases for biotechnological applications.

DNA Replication Mechanisms in Bacteriophages publication trend

The graph below shows the total number of articles in dna replication mechanisms in bacteriophages across all publications each year (not limited to Nature Index journals).

Technical terms

Replisome: Multiprotein complex responsible for DNA unwinding and synthesis at the replication fork.

Primase: Enzyme that synthesises short RNA primers to initiate DNA strand synthesis.

Helicase: ATP-dependent motor protein that separates double-stranded DNA into single strands ahead of the replication fork.

Single-stranded DNA binding protein (SSB): Protein that binds to unwound DNA, preventing secondary structures and stabilising the replication intermediate.

G-quadruplex (G4): Four-stranded DNA secondary structure formed by guanine-rich sequences that can hinder replication machinery.

References

1. T7 replisome directly overcomes DNA damage. Nature Communications (2015).
2. Joint Efforts of Replicative Helicase and SSB Ensure Inherent Replicative Tolerance of G‐Quadruplex. Advanced Science (2023).
3. Cooperative base pair melting by helicase and polymerase positioned one nucleotide from each other. eLife (2015).