Which protein acts as a sliding clamp to hold DNA polymerase to the template strand?

Which protein acts as a sliding clamp to hold DNA polymerase to the template strand?

• A. DNA polymerase
• B. Primase
• C. DNA ligase
• D. DNA sliding clamp

Answer: (D)

Keeping DNA polymerase attached to the DNA for long stretches is essential for rapid, accurate replication. The sliding clamp serves this role by forming a ring around the DNA and tethering the polymerase to the template, allowing it to synthesize many nucleotides before dissociating. In bacteria this ring is called the beta clamp; in eukaryotes it’s PCNA. The clamp is loaded onto DNA by a clamp loader in an ATP-dependent step and then works with the polymerase to boost processivity. The other enzymes have different jobs: DNA polymerase copies the DNA, primase makes RNA primers to start synthesis, and DNA ligase seals nicks between fragments. So the sliding clamp is the protein that holds the polymerase to the template.

Keeping DNA polymerase attached to the DNA for long stretches is essential for rapid, accurate replication. The sliding clamp serves this role by forming a ring around the DNA and tethering the polymerase to the template, allowing it to synthesize many nucleotides before dissociating. In bacteria this ring is called the beta clamp; in eukaryotes it’s PCNA. The clamp is loaded onto DNA by a clamp loader in an ATP-dependent step and then works with the polymerase to boost processivity. The other enzymes have different jobs: DNA polymerase copies the DNA, primase makes RNA primers to start synthesis, and DNA ligase seals nicks between fragments. So the sliding clamp is the protein that holds the polymerase to the template.