RNA-directed DNA polymerase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: deoxynucleoside triphosphate + DNA(n) = diphosphate + DNA(n+1). Catalyzes RNA-template-directed extension of the 3'- end of a DNA strand by one deoxynucleotide at a time. [EC:2.7.7.49]

RNA-directed DNA polymerase (RdRP) activity is a critical molecular function in the replication of certain viruses and retrotransposons. It refers to the enzymatic ability to synthesize DNA using an RNA template. This process is distinct from the typical DNA replication mechanism, which uses a DNA template.

RdRP enzymes are characterized by their unique ability to bind both RNA and DNA, enabling them to switch between RNA and DNA templates during replication. The mechanism involves several key steps:

1. **Template Binding:** The RdRP enzyme binds to the RNA template, recognizing specific sequences or structures.

2. **Initiation:** The enzyme initiates DNA synthesis by incorporating the first nucleotide, typically a deoxyribonucleotide, onto a primer molecule. The primer can be either a short RNA molecule or a DNA molecule.

3. **Elongation:** The RdRP enzyme then proceeds to elongate the DNA strand, adding deoxyribonucleotides complementary to the RNA template in a 5' to 3' direction. This process involves the formation of phosphodiester bonds between the nucleotides, catalyzed by the enzyme's polymerase activity.

4. **Termination:** The elongation process continues until the enzyme reaches a specific termination signal within the RNA template. At this point, the RdRP enzyme dissociates from the template, releasing the newly synthesized DNA molecule.

RdRP activity is essential for the replication of a wide range of viruses, including retroviruses, such as HIV, and RNA viruses, such as influenza and poliovirus. It is also involved in the transposition of certain retrotransposons, which are mobile genetic elements that can insert themselves into the host genome.

The unique mechanism of RdRP activity has made it a target for antiviral drug development. Several antiviral drugs, such as AZT (zidovudine), have been designed to inhibit RdRP activity, thereby blocking the replication of viruses.
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Proteins (1)

Compounds (28)