DNA repair is an important cellular process that ensures the integrity & stability of your genetic material, DNA (deoxyribonucleic acid).

DNA can be damaged in various ways, such as by exposure to toxins, pesticides, radiation, chemicals, and other environmental factors, as well as through errors that occur during DNA replication.

Unrepaired DNA damage can result in mutations, genomic instability, and diseases like cancer. To prevent these problems, cells have developed sophisticated DNA repair mechanisms and employ various DNA repair proteins for these tasks.

Here are a few examples of several primary types of DNA repair mechanisms, each designed to address specific types of DNA damage:

• Base Excision Repair (BER): BER is corrects small, non-helix-distorting lesions in DNA, such as damaged bases & single-strand breaks. DNA glycosylases are enzymes that initiate BER by removing the damaged base. Subsequent enzymes in the pathway replace the missing base & seal the gap.
• Nucleotide Excision Repair (NER): NER primarily repairs bulky DNA lesions that distort the double helix structure, such as those caused by UV radiation or certain chemicals. In NER, a set of proteins recognizes & removes a segment of DNA containing the lesion and then fills the gap with the correct nucleotides.
• Mismatch Repair (MMR): MMR corrects errors that occur during DNA replication, such as mismatches or small insertions/deletions. Key MMR proteins identify and remove the incorrect nucleotides & replace them with the correct ones.
• Double-Strand Break Repair (DSB Repair): Double-strand breaks in DNA are particularly dangerous and can lead to chromosomal rearrangements if not repaired properly. There are two main pathways for DSB repair: Non-Homologous End Joining (NHEJ) & Homologous Recombination (HR). NHEJ ligates the broken ends directly, while HR uses a homologous DNA template to repair the break accurately.
• Direct Reversal Repair: In some cases, DNA damage can be directly reversed without the need for excision and replacement of damaged bases. For example, DNA photolyases repair damage caused by UV light by directly reversing the DNA lesion.

In essence, DNA repair is a complex and highly regulated process.

At its core, DNA repair relies on specialized machinery: DNA repair proteins. Distinct proteins have distinct roles, each responsible for recognizing, processing, and mending specific forms of DNA damage.

There are numerous DNA repair proteins involved in various DNA repair pathways. DNA repair research continues to discover new proteins & gain insights into existing ones.

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Stay tuned the next episodes of the Protein series where we will dig into:

• Specific DNA repair proteins
• How they function
• Practical lifestyle tools for minimizing DNA damage
• How to support your DNA repair mechanisms... and MUCH more

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​In another episode of the Protein Series, I discussed the protein needs of older adults. If you have missed it, you can read about it here:​

​Aging Gracefully​ ​ ...the Truth About Protein Needs for Older Adults... ​ Read article

Disclaimer

This information is not medical advice. This content and other content on this website is for informational and educational purposes only and is not intended to be a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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References

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• Schärer OD. Nucleotide excision repair in eukaryotes. Cold Spring Harb Perspect Biol. 2013 Oct 1;5(10):a012609. doi: 10.1101/cshperspect.a012609. PMID: 24086042; PMCID: PMC3783044.
• Li GM. Mechanisms and functions of DNA mismatch repair. Cell Res18, 85–98 (2008).
• Lieber MR. The mechanism of double-strand DNA break repair by the nonhomologous DNA end-joining pathway. Annu Rev Biochem. 2010;79:181-211. doi: 10.1146/annurev.biochem.052308.093131. PMID: 20192759; PMCID: PMC3079308.
• Gutierrez R, O’Connor TR. DNA direct reversal repair and alkylating agent drug resistance. Cancer Drug Resist. 2021 Jun 19;4(2):414-423. doi: 10.20517/cdr.2020.113. PMID: 35582025; PMCID: PMC9019270.
• Liu Z, Wang L, Zhong D. Dynamics and mechanisms of DNA repair by photolyase. Phys Chem Chem Phys. 2015 May 14;17(18):11933-49. doi: 10.1039/c4cp05286b. PMID: 25870862; PMCID: PMC4447866.