Which protein is responsible for preventing the reformation of single-stranded DNA during replication?

The protein responsible for preventing the reformation of single-stranded DNA during replication is single-strand binding protein (SSB). During DNA replication, the double helix must be unwound to allow each strand to serve as a template for the formation of new strands. As the DNA unwinds, the individual strands become exposed and are vulnerable to re-annealing or forming secondary structures. Single-strand binding proteins bind to these exposed single-stranded regions, stabilizing them and preventing the strands from coming back together before the replication process can continue. This is crucial for ensuring that the DNA polymerase can effectively synthesize new DNA strands without interference from the reformation of the double helix.

Topoisomerase plays a different role by managing the torsional strain and supercoiling during unwinding. DNA polymerase III is the enzyme that synthesizes new DNA strands by adding nucleotides, and the RNA primer is essential for initiating DNA synthesis but does not prevent the reformation of single-stranded DNA. Therefore, single-strand binding proteins specifically address the issue of stabilizing single strands during the replication process.