| Title | Effects of the loss of mismatch repair genes on single-strand annealing between divergent sequences in Saccharomyces cerevisiae |
|---|---|
| Author | Ye-Seul Lim, Ju-Hee Choi, Kyu-Jin Ahn, Min-Ku Kim, and Sung-Ho Bae* |
| Address | Department of Biological Sciences, College of Natural Science, Inha University, Incheon 22212, Republic of Korea |
| Bibliography | Journal of Microbiology, 59(4),401–409, 2021, |
| DOI | 10.1007/s12275-021-1076-x |
| Key Words | single-strand annealing, mismatch repair, heteroduplex DNA, MSH2, MSH3, MSH6, hexose transporter gene, HO endonuclease, short-patch repair |
| Abstract | Eukaryotic genomes contain many duplicated genes closely located with each other, such as the hexose transporter (HXT) genes in Saccharomyces cerevisiae. They can potentially recombine via single-strand annealing (SSA) pathway. SSA between highly divergent sequences generates heteroduplex DNA intermediates with many mismatches, which can be corrected by mismatch repair (MMR), resulting in recombinant sequences with a single junction point. In this report, we demonstrate that SSA between HXT1 and HXT4 genes in MMR-deficient yeast cells produces recombinant genes with multiple-junctions resulting from alternating HXT1 and HXT4 tracts. The mutations in MMR genes had differential effects on SSA frequencies; msh6Δ mutation significantly stimulated SSA events, whereas msh2Δ and msh3Δ slightly suppressed it. We set up an assay that can identify a pair of recombinant genes derived from a single heteroduplex DNA. As a result, the recombinant genes with multiple-junctions were found to accompany genes with single-junctions. Based on the results presented here, a model was proposed to generate multiple-junctions in SSA pathway involving an alternative short-patch repair system. |