DNA glycosylase

Definition

DNA glycosylase is an enzyme that plays a crucial role in the DNA repair process by recognizing and removing damaged or mispaired bases from the DNA molecule. This action helps maintain the integrity of the genetic information, as these enzymes are essential for fixing DNA lesions that could lead to mutations or cellular dysfunction.

5 Must Know Facts For Your Next Test

1. DNA glycosylases initiate the base excision repair process by identifying and excising damaged bases, creating an apurinic/apyrimidinic (AP) site.
2. There are multiple types of DNA glycosylases, each specialized for different types of damaged bases, ensuring a broad spectrum of repair capabilities.
3. The removal of a damaged base by DNA glycosylase is typically followed by the action of an endonuclease and DNA polymerase, which work together to restore the correct sequence.
4. DNA glycosylases are crucial for protecting cells from mutations that can lead to diseases such as cancer, emphasizing their importance in genomic stability.
5. The activity of DNA glycosylases can be influenced by various factors including oxidative stress and aging, which may affect the overall efficiency of DNA repair mechanisms.

Review Questions

• How does DNA glycosylase contribute to the overall process of base excision repair?
  • DNA glycosylase is essential in base excision repair as it first identifies and removes damaged or incorrect bases from the DNA strand. Once a base is removed, it creates an apurinic/apyrimidinic (AP) site that signals other repair proteins to come in. These proteins then fill in the gap with the correct nucleotide, restoring the integrity of the DNA molecule and preventing potential mutations.
• Discuss the implications of dysfunctional DNA glycosylase activity on cellular health and disease development.
  • Dysfunctional DNA glycosylase activity can lead to an accumulation of DNA damage due to inefficient removal of damaged bases. This accumulation increases the risk of mutations, which can trigger oncogenic pathways and contribute to cancer development. Furthermore, impaired DNA repair mechanisms can also lead to cellular aging and various genetic disorders, highlighting the critical role of these enzymes in maintaining cellular health.
• Evaluate how environmental factors might influence the efficacy of DNA glycosylases in maintaining genomic stability.
  • Environmental factors such as oxidative stress and exposure to harmful substances can significantly impact the efficacy of DNA glycosylases. For instance, increased levels of reactive oxygen species can lead to more frequent damage to DNA bases, requiring efficient action from glycosylases. If these enzymes are overwhelmed or their function is impaired due to stress conditions, it could result in a decline in genomic stability. This might lead not only to increased mutation rates but also to more severe consequences like cancer or other genetic diseases, underscoring the intricate relationship between environmental factors and enzymatic activity in DNA repair.

Related terms

Base Excision Repair (BER): A cellular mechanism that repairs damaged DNA by removing and replacing individual bases, primarily involving DNA glycosylases.

Apurinic/apyrimidinic site (AP site): A location in DNA that has lost a purine or pyrimidine base, often resulting from the action of DNA glycosylases during repair.

Nucleotide Excision Repair (NER): A DNA repair mechanism that removes bulky DNA adducts and lesions, which is distinct from the base excision repair pathway.