RNA-dependent RNA polymerase

RNA-dependent RNA polymerase (RdRp) is an essential protein found in all RNA viruses. This enzyme is responsible for the replication of RNA from an RNA template, a process known as RNA replication. RdRp is the key component of the viral replication complex in RNA viruses.

Function

RdRp catalyzes the synthesis of a complementary RNA strand using a template RNA strand. The process of RNA replication by RdRp begins with the binding of the RdRp to the 3' end of the virus RNA, followed by the synthesis of a complementary RNA strand. The newly synthesized RNA strand then serves as a template for the synthesis of additional RNA strands.

Structure

The structure of RdRp is highly conserved among RNA viruses, indicating a common evolutionary origin. The core structure of RdRp is a right-handed domain structure, which resembles a cupped hand. This structure is composed of three subdomains: the fingers, palm, and thumb subdomains. The active site of the enzyme, where RNA synthesis occurs, is located in the palm subdomain.

Role in Viral Replication

In RNA viruses, RdRp is essential for the replication of the viral genome. The enzyme synthesizes a negative-sense RNA strand using the positive-sense RNA genome of the virus as a template. This negative-sense RNA strand then serves as a template for the synthesis of additional positive-sense RNA genomes.

Inhibitors

Given the essential role of RdRp in the life cycle of RNA viruses, this enzyme is a major target for antiviral drugs. Several RdRp inhibitors have been developed for the treatment of infections caused by RNA viruses, such as Hepatitis C and COVID-19.

See Also

• RNA virus
• Viral replication
• Antiviral drug