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DNA polymerase I (or Pol I) is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956, [1] it was the first known DNA polymerase (and the first known of any kind of polymerase). It was initially characterized in E. coli and is ubiquitous in prokaryotes.
The E. Coli DnaG primase is a 581 residue monomeric protein with three functional domains, according to proteolysis studies. There is an N-terminal Zinc-binding domain (residues 1–110) where a zinc ion is tetrahedrally coordinated between one histidine and three cysteine residues, which plays a role in recognizing sequence specific DNA binding sites.
The Klenow fragment is a large protein fragment produced when DNA polymerase I from E. coli is enzymatically cleaved by the protease subtilisin.First reported in 1970, [1] it retains the 5' → 3' polymerase activity and the 3’ → 5’ exonuclease activity for removal of precoding nucleotides and proofreading, but loses its 5' → 3' exonuclease activity.
A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create two identical DNA duplexes from a single original DNA duplex.
In prokaryotes, the FEN enzyme is found as an N-terminal domain of DNA polymerase I, but some prokaryotes appear to encode a second homologue. [ 1 ] [ 2 ] [ 3 ] The endonuclease activity of FENs was initially identified as acting on a DNA duplex which has a single-stranded 5' overhang on one of the strands [ 4 ] (termed a "5' flap", hence the ...
Structure of Taq DNA polymerase. In biochemistry, a polymerase is an enzyme (EC 2.7.7.6/7/19/48/49) that synthesizes long chains of polymers or nucleic acids. DNA polymerase and RNA polymerase are used to assemble DNA and RNA molecules, respectively, by copying a DNA template strand using base-pairing interactions or RNA by half ladder replication.
Taq polymerase exonuclease is a domain found in the amino-terminal of Taq DNA polymerase I (thermostable). It assumes a ribonuclease H-like motif . The domain confers 5' -3' exonuclease activity to the polymerase.
DNA polymerase I removes the primer, replacing it with DNA, and DNA ligase joins the ends to make another molecule of double-stranded circular DNA. As a summary, a typical DNA rolling circle replication has five steps: [2] Circular dsDNA will be "nicked". The 3' end is elongated using "unnicked" DNA as leading strand (template); 5' end is ...