Y Family Polymerases
Y Family Polymerases - Related Videos
02:47
Protein Families
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2020
Protein families are groups of homologous proteins; that is, they have similarities in amino acid sequences and three-dimensional structures. Protein families usually occur because of gene duplication, where an additional copy of a gene is inserted into the genome of an organism. Mutations that change the amino acids but still allow the protein to be properly synthesized, will lead to new protein family members. If these new proteins contain similar amino acids in key locations, protein...
01:57
Gene Families
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2020
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate. Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
02:10
Translesion DNA Polymerases
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2020
Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication. TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
00:58
Eukaryotic RNA Polymerases
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2025
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action. All three eukaryotic RNAPs require specific transcription factors, of which the...
00:43
Bacterial RNA Polymerase
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2020
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity. In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
FAQs
Their active sites are more open and flexible than those of high-fidelity polymerases. This architecture can accommodate damaged or chemically modified bases that would obstruct a tighter active site. The same flexibility supports lesion bypass, but it reduces nucleotide-selection precision, creating a fundamental tradeoff between replication continuity and accuracy.
During translesion DNA synthesis, a Y family polymerase first inserts a nucleotide opposite a lesion and can then extend beyond the damaged site. This two-part capability matters because an obstructed replication fork can otherwise fail to progress. By permitting continued synthesis, the enzymes help cells tolerate damage while also creating opportunities for inaccurate copying.
Reduced accuracy arises from the relaxed nucleotide-selection properties associated with their flexible active sites. When a lesion is bypassed, the inserted nucleotide or subsequent extension can be incorrect, so replication proceeds at the cost of potential sequence changes. This explains why these enzymes connect DNA damage tolerance with mutagenesis and why their activity has consequences beyond simply restoring fork movement.
High-fidelity DNA polymerases prioritize accurate nucleotide selection during normal DNA replication, whereas Y family polymerases have more open, flexible active sites. That difference gives the specialized enzymes greater ability to copy across damaged bases, but with reduced accuracy. The two polymerase groups therefore represent complementary strategies: routine precision versus lesion bypass when replication encounters damage.
Their relevance is greatest when normal replication encounters damaged or chemically modified bases and replication stress threatens fork progression. In that setting, studying these enzymes helps explain how cells maintain replication continuity despite DNA damage. The topic therefore informs research on damage tolerance, replication-fork behavior, and mechanisms that preserve genome stability.
It connects molecular lesion bypass with broader cellular outcomes. Researchers can use this framework to examine how error-prone synthesis contributes to mutagenesis, how damage responses influence genome stability, and how cells adapt to replication stress. These questions place Y family polymerases within biology as a link between DNA damage, replication dynamics, and cellular adaptation.