Role of Microhomology in the Repair of Double-Stranded DNA breaks in Saccharomyces cerevisiae

Microhomology-mediated end-joining (MMEJ) is an error-prone DNA double-strand break repair pathway. The high mutation and genome rearrangement rates associated with MMEJ contribute to genetic plasticity but may also induce malignancy, generating significant research interest. Previous MMEJ studies have examined the use of microhomologies (MH) on either side of a double-strand break to facilitate repair. However, little evidence shows the involvement of MH in double-strand break repair (DSBR). Using Saccharomyces cerevisiae , we demonstrate the use of MH in DSBR of an induced double-strand break, which is influenced by MH length and continuity. In contrast, MH did not facilitate break-induced replication under similar circumstances. Although the frequency of homologous recombination using MH is comparatively low, it still represents a potential pathway for genome rearrangements and loss of heterozygosity in regions containing short repetitive sequences.