Which is the most processive of prokaryotic DNA polymerases

Among prokaryotic DNA polymerases, DNA polymerase III (Pol III) is generally considered the most processive. Pol III is the primary replicative polymerase responsible for DNA replication in bacteria, and it exhibits high processivity, meaning it can catalyze the addition of multiple nucleotides to a growing DNA strand without dissociating from the template DNA.

The processivity of Pol III is conferred by its association with a multi-protein complex known as the DNA polymerase III holoenzyme. This holoenzyme consists of several subunits, including the core polymerase subunit (Pol III core) responsible for catalyzing DNA synthesis, as well as other accessory proteins involved in DNA replication, such as the β-clamp (also known as the sliding clamp), clamp loader complex, and exonuclease subunits.

The β-clamp, in particular, plays a crucial role in enhancing the processivity of Pol III. It forms a ring-shaped structure that encircles the DNA template and acts as a sliding clamp, tethering the polymerase to the DNA and allowing it to remain associated with the template strand during DNA synthesis. This interaction increases the efficiency and speed of DNA replication by preventing the polymerase from dissociating prematurely.

Overall, DNA polymerase III, in conjunction with its associated proteins in the DNA polymerase III holoenzyme complex, exhibits remarkable processivity, making it the primary replicative polymerase responsible for synthesizing the majority of the bacterial genome during DNA replication.