Replisome DNA synthesis

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Part 2
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Replisome DNA synthesis
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(continued)
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(continued)
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(continued)
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Initiation and Termination of DNA Replication

• Replisome assembles at origin site (oriC)
• Initial assembly depends on unwinding of the DNA
  caused by binding certain proteins
• DnaA is one initiation protein

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Termination site (ter)

• Terminator utilization substance (Tus) binds to
  the ter site
• Tus inhibits helicase activity and thus prevents
  replication forks continuing through this region

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Origin (oriC) and terminus (ter) of DNA
replication in E. coli

• dnaA is gene for protein DnaA (required to
  initiate replication)
• Red arrows indicate direction of movement of
  replication forks

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E. coli Tus bound to DNA

• Tus binds to specific sequences at the
  termination site of DNA replication
• Tus blocks movement of the replisome

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DNA Replication in Eukaryotes

• Mechanism similar to that in prokaryotes leading
  strand continuous synthesis, lagging strand
  discontinuous synthesis
• Replication forks move more slowly, but many
  replication forks
• Okazaki fragments are shorter in eukaryotes
  (100-200 residues)
• At least 5 different DNA polymerases

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Moran et al 2006