There are five different DNA dependent DNA polymerases in E. coli bacteria: DNA polymerase I, II, III, IV and V. DNA polymerase III is the primary enzyme involved in DNA replication, forming a high-speed, high-fidelity multiprotein complex. DNA polymerases IV and V are Y-family polymerases that replicate damaged DNA with lower fidelity than polymerase III. DNA polymerases I and II serve backup roles in DNA repair through their exonuclease activities when the template is damaged.

2. •DNA POLYMERASES CATALYZE THE SYNTHESIS OF DNA.
•IN EUBACTERIA SUCH AS E.coli, THERE ARE FIVE
DIFFERENT DNA DEPENDENT DNA POLYMERASE, THESE
ARE DNA POLYMERASE I,II,III,IV and V.
DNA
POLYMERASE
TEMPLATE
DEPENDENT
DNA
DEPENDENT
RNA
DEPENDENT
TEMPLATE
INDEPENDENT

3. • ALSO KNOWN AS KORNBERG ENZYME.
• 5’→3’ POLYMERASE ACTIVITY.
• 5’→3’ AND 3’→5’ EXONUCLEASE ACTIVITY.
• LOW PROCESSIVITY.
• PERFORM FUNCTIONS SUCH AS PRIMER
REMOVAL, GAP FILLING AND DNA REPAIR.
DNA
POLYMERASE
I
• 5’→3’ POLYMERASE ACTIVITY.
• 3’→5’ EXONUCLEASE ACTIVITY.
• LOW PROCESSIVITY.
• SERVES AS AN ALTERNATIVE DNA REPAIR
POLYMERASE, IT CAN ALSO REPLICATE DNA
IF THE TEMPLATE IS DAMAGED.
DNA
POLYMERASE
II

4. • IT IS THE PRIMARY ENZYME
INVOLVED IN DNA REPLICATION.
• MULTIPROTEIN COMPLEX.
• HIGH POLYMERIZATION RATE AND
HIGH PROCESSIVITY.
DNA
POLYMERASE
III
DNA POLYMERASE III HOLOENZYME

5. • Y- FAMILY DNA POLYMERASES.
• DO NOT CONTAIN 3’→5’
EXONUCLEASE ACTIVITY.
• LOW CATALYTIC EFFICIENCY, LOW
PROCESSIVITY AND LOW FIDELITY.
• INVOLVED IN THE TRANSLESSION
SYNTHESIS AND REPLICATE
DAMAGED DNA.
DNA
POLYMERASE
IV
AND
DNA
POLYMERASE
V