What is the Difference Between Taq Polymerase and DNA Polymerase

The main difference between Taq polymerase and DNA polymerase is that Taq polymerase is the thermostable DNA polymerase while DNA polymerase is the enzyme that catalyzes the synthesis of DNA molecules.

Taq polymerase and DNA polymerase are two types of enzymes that catalyze the synthesis of DNA molecules. However, Taq DNA polymerase is responsible for the DNA synthesis in in-vitro systems such as in PCR while DNA polymerase is responsible for the DNA synthesis inside the cell.

Key Areas Covered

1. What is Taq Polymerase
   • Definition, Characteristics, Importance
2. What is DNA Polymerase
   • Definition, Characteristics, Importance
3. Similarities Between Taq Polymerase and DNA Polymerase
   • Outline of Common Features
4. Difference Between Taq Polymerase and DNA Polymerase
   • Comparison of Key Differences

Key Terms

DNA Polymerase, DNA polymerase I, II, III, IV, and V, Taq Polymerase

What is Taq Polymerase

Taq polymerase is the most common DNA polymerase type used in the PCR amplification of DNA. The main feature of Taq polymerase is that it is heat resistant. It has a half-life of 40 minutes at 95°C. In addition, its optimal temperature is 72°C and it adds 2–4 kilobases per minute at its optimal temperature. Since it is active in a broad range of temperatures, Taq polymerase adds nucleotides and, if DNA and primers are available, mispriming and elongation may occur.

Figure 1: Taq Polymerase

Furthermore, Taq polymerase is named after the thermophilic eubacterial microorganism Thermus aquaticus. T. aquaticus is a bacterium that lives in hot springs and hydrothermal vents, and Taq polymerase was identified as an enzyme able to withstand the protein-denaturing conditions (high temperature) required during PCR. Therefore, it replaced the DNA polymerase from E. coli originally used in PCR.

What is a DNA Polymerase

DNA polymerase is the enzyme responsible for the synthesis of DNA inside the cell. Some of the significant features of DNA polymerase include the addition of nucleotides in the 5′ to 3′ direction on the growing strand and the requirement of an RNA primer – in other words, a pre-existing 3′-OH group for the initiation of synthesis. Generally, in eukaryotes, six types of DNA polymerases occur: they are the DNA polymerases α, β, γ, δ, ε, and ζ. However, only α, δ, and ε polymerases take part in DNA replication. Other DNA polymerases take part in DNA repair.

Figure 2: DNA Polymerase

Moreover, the main types of DNA polymerases that occur in prokaryotes include DNA polymerase I, II, III, IV, and V. Here, DNA polymerase I has both 3′ to 5′ and 5′ to 3′ exonuclease activity. Additionally, DNA polymerase II only has 3′ to 5′ exonuclease activity. Meanwhile, DNA polymerase III holoenzyme is the main enzyme responsible for DNA replication in prokaryotes. On the contrary, DNA polymerase IV takes part in non-targeted mutagenesis. DNA polymerase V takes part in DNA repair.

Similarities Between Taq Polymerase and DNA Polymerase

• Taq polymerase and DNA polymerase are two types of enzymes responsible for DNA synthesis.
• Their function is to add DNA nucleotides to the 3’ OH ends.

Difference Between Taq Polymerase and DNA Polymerase

Definition

Taq polymerase refers to the heat-stable (thermostable) DNA polymerase extracted from the thermophilic bacteria Thermus aquaticus, while DNA polymerase refers to a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.

Occurs in

Usually, Taq polymerase occurs in T. aquaticus while DNA polymerase occurs in prokaryotes.

Optimal Temperature

The optimal temperature of Taq polymerase is 72°C while the optimal temperature of DNA polymerase is 37°C.

High Temperatures

Taq polymerase is active in high temperatures while DNA polymerase is not active at high temperatures.

Processivity

Taq polymerase adds 2–4 kilobases per minute while DNA polymerase adds ~15-20 nucleotides per second.

Application

Moreover, Taq polymerase is used in PCR while DNA polymerase is used in prokaryotic cells to synthesize DNA.

Conclusion

In brief, Taq polymerase is a thermal resistant form of DNA polymerase I that occur in T. aquaticus. Its optimal temperature is 72°C. Therefore, this DNA polymerase is thermostable. However, DNA polymerase is a prokaryotic enzyme responsible for the synthesis of DNA inside the cell. Its optimal temperature is 37°C. Therefore, the main difference between Taq polymerase and DNA polymerase is their optimal temperature.

References:

1. Taq polymerase. Taq Polymerase – an overview | ScienceDirect Topics. (n.d.). Retrieved September 6, 2022.
2. Mandal, D. A. (2022, June 15). What is DNA polymerase? Retrieved September 6, 2022.

Image Courtesy:

1. “Taq polimerase ” By Lijealso – Own Work (Public Domain) via Commons Wikimedia
2. “DNA polymerase ” By Yikrazuul – Own Work (CC By-SA 3.0) via Commons Wikimedia