DNA replication

  1. Proofreading
    3’ to 5’ exonuclease activity of DNA polymerase responsible for removing an incorrectly incorporated nucleotide
  2. Telomerases
    a reverse transcriptase (synthesize DNA from an RNA template) responsible for replicating the tandem repeats of simple-sequence DNA at the telomeres
  3. Topoisomerase
    enzymes that catalyze the reversible breakage and rejoining of DNA strands to prevent the unchecked rotation of DNA that occurs ahead of the replication fork. The breaks serve as “swivels” that allow the two strands of template DNA to rotate freely around each other so that replication can proceed without twisting the DNA ahead of the fork.
  4. Single-stranded DNA-binding proteins (replication factor A)
    stabilize the unwound template DNA, keeping it in an extended single-stranded state so that it can be copied by the polymerase
  5. Clamp-loading proteins = replication factor C (RFC)
    specifically recognize and bind DNA at the junction between the primer and template. After binding of the sliding-clamp protein, clamp proteins then load the DNA polymerase onto DNA at the primer-template junction.
  6. Origin-binding proteins
    multimeric protein complex responsible for recognizing the origin of replication; one member of this complex, the initiator protein, which unwinds the origin DNA and recruits the other proteins involved in synthesis
  7. DNA polymerase
    catalyzes the joining of deoxyribonucleotide 5’-triphosphates (dNTPs) to form the growing DNA chain; synthesizes DNA only in the 5’ to 3’ direction; can add a new dNTP only to a preformed primer strand that is hydrogen bonded to the template; dimerizes
Card Set
DNA replication
DNA replication