Researchers Reveal DNA Repair Mechanism
Published:17 Jul.2023 Source:NYU Langone Health / NYU Grossman School of Medicine
A new study adds to an emerging, radically new picture of how bacterial cells continually repair faulty sections of their DNA. The report describes the molecular mechanism behind a DNA repair pathway that counters the mistaken inclusion of a certain type of molecular building block, ribonucleotides, into genetic codes. Such mistakes are frequent in code-copying process in bacteria and other organisms. Given that ribonucleotide misincorporation can result in detrimental DNA code changes (mutations) and DNA breaks, all organisms have evolved to have a DNA repair pathway called ribonucleotide excision repair (RER) that quickly fixes such errors.
Researchers found that most of the repair of certain types of DNA damage (bulky lesions), such as those caused by UV irradiation, can occur because damaged code sections have first been identified by a protein machine called RNA polymerase, and during this transcription process, RNA polymerase also finds DNA lesions, and then serves as a platform for the assembly of a DNA repair machine called nucleotide excision repair (NER) complex. Now the new study provides the first evidence that, like in the NER pathway, RER is tightly coupled to transcription.
This work supports a model where RNaseHII scans DNA for misplaced ribonucleotides by riding on RNA polymerase while it moves along DNA, and is vital for our basic understanding of the DNA repair process and has far-reaching clinical implications."