Replisomi

Replisomi is the term used to describe the multiprotein complex that carries out DNA replication at replication forks in cells. It coordinates DNA unwinding by helicases, primer synthesis by primases, and DNA synthesis by DNA polymerases, integrating leading- and lagging-strand synthesis and providing processivity via sliding clamps. In bacteria, the core replisome includes the DnaB helicase, the DnaG primase, the DNA polymerase III holoenzyme, the sliding clamp (β clamp), and the clamp-loader complex (γ-complex), together with single-strand DNA-binding protein (SSB) and topoisomerases. In eukaryotes, the equivalent machine is the CMG helicase complex (Cdc45–MCM2-7–GINS) paired with DNA polymerases α, δ, and ε, PCNA as the sliding clamp, RFC as the clamp loader, and RPA for protection of single-stranded DNA. Accessory factors ensure correct assembly, fork progression, and replication stress responses.

Replisomes are dynamic assemblies that rapidly assemble at origins of replication, migrate with the fork as DNA is unwound, and disassemble after replication. They coordinate checkpoint signaling and may recruit repair pathways if damage is encountered. Disruption of replisome function can lead to replication fork collapse and genome instability, making replisome components important in studies of cell biology and antimicrobial strategies.

This article uses the term Replisomi to refer to the central replication machinery shared by diverse life forms, noting both conserved core functions and organism-specific adaptations.