Question

Which both E. coli polymerases are used in translesion replication (SOS repair of damaged DNA, e.g. repair of thymidine dimers)?

a DNA polymerase V and III
b DNA polymerase IV and I
c DNA polymerase IV and V
d DNA polymerase II and III

Answer 1

In E. coli, DNA polymerase IV (pol IV) and DNA polymerase V (pol V) are involved in translesion synthesis during SOS repair of damaged DNA like thymidine dimers.

Step-by-step explanation:

In the process of translesion synthesis or SOS repair, a mechanism bacteria use to bypass DNA damage, E. coli employs different polymerases for DNA repair and replication. Typically, DNA pol III is the enzyme required for DNA synthesis, while DNA pol I and DNA pol II are primarily involved in repair. However, during SOS repair, the standard DNA replication machinery including DNA pol III may stall at sites of extensive DNA damage such as thymidine dimers.

DNA polymerase V (pol V) and DNA polymerase IV (pol IV) are specifically known for their roles in translesion synthesis. These polymerases are able to incorporate nucleotides opposite damaged bases, allowing the replication fork to move past the lesion. Thus, for the SOS repair of damaged DNA such as thymidine dimers, the correct answer is DNA polymerase IV (pol IV) and DNA polymerase V (pol V), making option c the correct choice.