page_title: T7 DNA polymerase
section_title: Accessory proteins
hierarchical_section_title: T7 DNA polymerase / Accessory proteins
caption_attribution_description: English: gp4 helicase domain unwinds double-stranded DNA into two single-stranded DNA template. Primase domain adds oligoribonucleotide primers. gp5/thioredoxin catalyzes synthesis of leading and lagging strands. gp2.5 coats the single-stranded DNA produced during replication. Interactions between gp5/thioredoxin and accessory proteins contributes to higher processivity in replisome assembly compared to gp5.
context_page_description: T7 DNA polymerase is an enzyme used during the DNA replication of the T7 bacteriophage. During this process, the DNA polymerase “reads” existing DNA strands and creates two new strands that match the existing ones. The T7 DNA polymerase requires a host factor, E. coli thioredoxin, in order to carry out its function. This helps stabilize the binding of the necessary protein to the primer-template to improve processivity by more than 100-fold, which is a feature unique to this enzyme. It is a member of the Family A DNA polymerases, which include E. coli DNA polymerase I and Taq DNA polymerase.
  This polymerase has various applications in site-directed mutagenesis as well as a high-fidelity enzyme suitable for PCR. It has also served as the precursor to Sequenase, an engineered-enzyme optimized for DNA sequencing.
context_section_description: While phage T7 mediates DNA replication in very similar manner to higher organisms, T7 system is generally simpler compared to other replication systems. In addition to T7 DNA polymerase (also known as gp5), T7 replisome requires only four accessory proteins for proper function: host thioredoxin, gp4, gp2.5, and gp1.7.
caption: Figure 4. Phage T7 replication machinery. gp4 helicase domain unwinds double-stranded DNA into two single-stranded DNA template. Primase domain adds oligoribonucleotide primers. T7 polymerase/thioredoxin catalyzes synthesis of leading stand and lagging strand. gp2.5 coats the single-stranded DNA produced during replication. Interactions between T7 polymerase/thioredoxin and accessory proteins contributes to higher processivity in replisome assembly compared to gp5.
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