Which repair mechanism is utilized to correct small, non-helix-deforming adducts?

Base excision repair is the correct mechanism for correcting small, non-helix-deforming adducts. This repair system is particularly specialized for recognizing and removing damaged or non-canonical bases that may arise from metabolic processes or environmental factors.

The process begins when a DNA glycosylase enzyme recognizes the specific type of damaged base and cleaves the bond between the base and the sugar backbone, creating an abasic site. Following this, an AP endonuclease cuts the DNA backbone at this site, and DNA polymerase fills in the gap with the correct nucleotide. Finally, DNA ligase seals the strand, restoring the integrity of the DNA.

In contrast, double-strand break repair addresses more significant damages involving breaks in both strands of the DNA helix, while nucleotide excision repair targets bulky, helix-distorting lesions, and mismatch repair focuses on correcting base pairing errors that emerge during DNA replication. Each of these repair mechanisms is tailored to specific types of DNA damage, making base excision repair the ideal choice for small, non-helix-deforming adducts.