High-Fidelity DNA Polymerases: Do You Know Their "Superpowers"?
The discovery and application of DNA polymerases in the 1980s brought a revolutionary change to the field of biotechnology, promoting the development of various techniques such as high-fidelity PCR, nested PCR, multiplex PCR, quantitative PCR (qPCR), reverse transcription polymerase chain reaction (RT-PCR), and whole-genome amplification. The emergence of these technologies greatly advanced research in genomics, molecular biology, and biomedicine. In the three domains of life—bacteria, archaea, and eukaryotes—DNA polymerases have evolved distinct functions and characteristics.
Bacteria mainly rely on Pol III for genome replication, while Pol I is responsible for Okazaki fragment maturation and RNA primer removal. In archaea, Pol B is the primary replicative enzyme and possesses both polymerase and 3′→5′ proofreading activity. In eukaryotes, Pol α, Pol δ, and Pol ε—members of the B family—complete chromosomal DNA replication. These enzymes are all multi-subunit complexes with high fidelity and essential proofreading functions.
DNA polymerases are classified into several families based on their sequence and function, including families A, B, C, D, X, Y, RT, and PrimPol. Each family of enzymes has unique domains and functional characteristics. For example, A family polymerase Pol I participates in Okazaki fragment maturation and DNA repair; B family polymerases Pol α, Pol δ, and Pol ε are the major replicative enzymes in eukaryotes; and Y family enzymes are involved in translesion synthesis (TLS). The structural domains of these enzymes include palm, thumb, fingers, and little finger regions. The palm domain contains the catalytic center, the thumb domain binds the DNA substrate, the fingers domain is involved in base pairing, and the exonuclease domain plays a crucial role in DNA binding.
The high fidelity of DNA polymerases is key to genomic stability, and their accuracy is determined by the combined action of conformational selection, Mg²⁺-mediated chemical selection, and proofreading functions. Conformational selection ensures that only correctly paired dNTPs can stabilize the ternary complex to facilitate DNA synthesis. The binding of Mg²⁺ ions is critical for dNTP correctness; incorrect dNTPs cannot bind stably, thus reducing the probability of misincorporation. The 3′→5′ exonuclease activity can recognize and remove misincorporated nucleotides, significantly improving the fidelity of DNA synthesis. These coordinated mechanisms enable DNA polymerases to play an essential role in genome replication and maintenance.
Biology: Cell Structure I Nucleus Medical Media
High-Fidelity DNA Polymerase
High-fidelity DNA polymerases replicate DNA templates with high accuracy. Their strong 3′→5′ exonuclease activity enables correction of misincorporated nucleotides, significantly enhancing replication accuracy.These enzymes not only possess 5′→3′ polymerase activity to synthesize DNA along the template strand but also reduce mutation rates through their proofreading function.