translesjonssyntesepolymeraser

Translesion synthesis polymerases, often abbreviated TLS polymerases, are a specialized group of enzymes crucial for DNA repair. Unlike replicative DNA polymerases that accurately copy intact DNA strands, TLS polymerases are designed to bypass DNA lesions. These lesions are structural abnormalities in the DNA that can stall or block the normal replication machinery, potentially leading to cell death or mutations.

TLS polymerases achieve bypass by having active sites that can accommodate damaged bases. While they can insert a nucleotide opposite a damaged base, their fidelity is generally lower than that of replicative polymerases. This means they are more prone to incorporating incorrect nucleotides, which can result in point mutations. However, this error-prone nature is often a trade-off for survival, as it allows the cell to continue replicating its DNA in the presence of damage that would otherwise halt the process.

These polymerases play a vital role in maintaining genomic integrity by preventing replication fork collapse. They are recruited to stalled replication forks and insert a nucleotide opposite the lesion. In many cases, a subsequent, more accurate replicative polymerase then takes over to complete the synthesis, effectively replacing the TLS polymerase and sometimes correcting any errors introduced. The human genome encodes several TLS polymerases, each with varying substrate specificities and error rates, contributing to a diverse DNA repair network.