| Component | Function |
|---|---|
| Initiator protein | Binds to origin and separates strands of DNA to initiate replication |
| DNA helicase | Unwinds DNA at replication fork |
| Single-strand-binding proteins | Attach to single-stranded DNA and prevent secondary structures from forming |
| DNA gyrase | Moves ahead of the replication fork, making and resealing breaks in the double-helical DNA to release the torque that builds up as a result of unwinding at the replication fork |
| DNA primase | Synthesizes a short RNA primer to provide a 3′-OH group for the attachment of DNA nucleotides |
| DNA polymerase III | Elongates a new nucleotide strand from the 3′-OH group provided by the primer |
| DNA polymerase I | Removes RNA primers and replaces them with DNA |
| DNA ligase | Joins Okazaki fragments by sealing breaks in the sugar–phosphate backbone of newly synthesized DNA |