Final answer:
DNA polymerase III achieves high processivity through its oligomeric structure, which allows tight binding to DNA, and its proofreading ability that ensures high fidelity of DNA synthesis. The enzyme works in conjunction with other replication proteins and uses energy from nucleotide triphosphates to add nucleotides efficiently to the growing DNA chain.
Step-by-step explanation:
How DNA Polymerase III Achieves High Processivity
DNA polymerase III is an enzyme with the critical role of synthesizing new strands of DNA during replication. One of its remarkable features is its high processivity, meaning it can add a large number of nucleotides to a growing DNA strand without dissociating.
To achieve this, DNA polymerase III, which is an oligomeric protein complex, has a high affinity for DNA and uses its structure to tightly grip the DNA strand. It synthesizes the daughter DNA strand using the template strand, adding nucleotides in the 5' to 3' direction. The enzyme’s proofreading ability further enhances its processivity and fidelity, as it can quickly correct mistakes by removing mismatched nucleotides and resuming DNA synthesis.
The enzyme also works in conjunction with other proteins and enzymes involved in the replication process, such as DNA helicases, topoisomerases, single-strand binding proteins, primase, and DNA ligase. This coordination ensures a continuous and efficient replication process. Furthermore, the use of an RNA primer synthesized by primase allows DNA polymerase III to begin the DNA synthesis process by providing a free 3'-OH group needed for nucleotide addition.
Energy for the catalyzation of the growing DNA chain is supplied by nucleotides with three phosphate groups attached. When these bonds are broken, the energy released is used to form the phosphodiester bonds essential for stringing together individual nucleotides and extending the DNA chain.