| Component |
Function |
| Initiator proteins |
Bind to origin and separate strands of DNA to initiate replication |
| DNA helicase |
Unwinds DNA at replication fork |
| Single-strand-binding proteins |
Attach to single-stranded DNA proteins and prevent secondary structures from forming |
| DNA gyrase |
Moves ahead of the replication fork, making and resealing breaks in the double-stranded 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 |