DNA polymerase: Difference between revisions
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==Overview== | ==Overview== | ||
'''DNA polymerases''' are enzymes that play a key role in [[DNA]] replication. '''DNA replication''' is the process of splitting an existing double-stranded DNA molecule into two single strands of DNA, then using DNA polymerases to translate the single strands. The process of translation results in the creation of the '''complementary''' DNA strands and results in the creation of two double-stranded DNA molecules that are exact replicas of the original DNA molecule. The complementary strands are created in the 5'-3' direction. Certain DNA polymerases are also responsible for proofreading the newly synthesized DNA strand and using exonuclease to remove and replace any errors that occurred. DNA polymerases are divided into 7 families according to their sequence homology and 3D structure similarities.<ref>PMID:10364165</ref> The families are: | '''DNA polymerases''' are enzymes that play a key role in [[DNA]] replication. '''DNA replication''' is the process of splitting an existing double-stranded DNA molecule into two single strands of DNA, then using DNA polymerases to translate the single strands. The process of translation results in the creation of the '''complementary''' DNA strands and results in the creation of two double-stranded DNA molecules that are exact replicas of the original DNA molecule. The complementary strands are created in the 5'-3' direction. Certain DNA polymerases are also responsible for proofreading the newly synthesized DNA strand and using exonuclease to remove and replace any errors that occurred. DNA polymerases are divided into 7 families according to their sequence homology and 3D structure similarities.<ref name='SteitzJBiolChem1999'>PMID:10364165</ref> The families are: | ||
* Family A - DNA replication and repair (DNA Polymerase I, γ) | * Family A - DNA replication and repair (DNA Polymerase I, γ) | ||
* Family B - DNA replication and repair (DNA Polymerase II, α, δ, ε). See [[DNA Polymerase in Thermococcus gorgonarius]]. | * Family B - DNA replication and repair (DNA Polymerase II, α, δ, ε). See [[DNA Polymerase in Thermococcus gorgonarius]]. | ||
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==Types of DNA Polymerase== | ==Types of DNA Polymerase== | ||
According to their sequence homology and 3D structure similarities, DNA Polymerases can be divided into 7 families: A, B, C, D, X, Y, and RT | According to their sequence homology and 3D structure similarities, DNA Polymerases can be divided into 7 families: A, B, C, D, X, Y, and RT <ref name='SteitzJBiolChem1999'/>. | ||
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==Mechanism== | ==Mechanism== | ||
The majority of DNA polymerases undergo a two-metal-ion mechanism. Two metal ions in the active site work to stabilize the pentacoordinated transition state. The first metal ion activates the hydroxyl groups. Those hydroxyl groups then go on to attack the phosphate group of the dNTP. The second metal ion not only stabilizes the negative charge, but also builds on the leaving oxygen and chelating phosphate groups. <ref | The majority of DNA polymerases undergo a two-metal-ion mechanism. Two metal ions in the active site work to stabilize the pentacoordinated transition state. The first metal ion activates the hydroxyl groups. Those hydroxyl groups then go on to attack the phosphate group of the dNTP. The second metal ion not only stabilizes the negative charge, but also builds on the leaving oxygen and chelating phosphate groups. <ref name='SteitzJBiolChem1999'/> | ||
