As DNA is passed on from generation to generation, scientists previously believed it would need to have a stable structure in order to maintain the genetic information. However, DNA is in fact a highly reactive molecule. Yes it needs to be stable enough to maintain the genetic information, but it also has to be reactive enough to allow evolution. This reactivity, however, also makes the DNA prone to damage. DNA damage can be external, like from the environment, or internal, like a number of the cell's own metabolites. These damages must of course be repaired, otherwise they may lead to diseases such as cancers. There are already enzymes known to be involved in DNA repair, and now there’s a new addition.
New DNA Repair Enzyme
The newly discovered DNA repair enzyme called AlkD is a DNA glycosylase, a family of enzymes that removes damaged DNA bases through base-excision repair. Researchers determined that the enzyme is able to locate damaged DNA that has a positive electrical charge. This positive charge corresponds to alkylation, the attachment of alkyl groups to specific positions on the damaged base. Positively charged alkylated bases are among the most abundant and detrimental forms of DNA damage. AlkD recognizes damaged bases indirectly as it only interacts with the DNA backbone. It can repair different types of lesions as long as they are positively charged. Moreover, it can do so even if the lesion is bulky. These traits are unlike other glycosylases.
Although AlkD was discovered in bacteria, humans may have DNA-repair enzymes that operate in a similar fashion to remove complex types of DNA damage. These could have clinical relevance because these enzymes, if they exist, could be reducing the effectiveness of drugs designed to kill cancer cells by shutting down their ability to replicate.