Minisatellite variants generated in yeast meiosis involve DNA removal during gene conversion

Two yeast minisatellite alleles were cloned and inserted into a genetically defined interval in Saccharomyces cerevisiae. Analysis of flanking markers in combination with sequencing allowed the determination of the meiotic ev ents that produced minisatellites with altered lengths. Tetrad analysis rev ealed that gene conversions, deletions, or complex combinations of both wer e involved in producing minisatellite variants. Similar changes were obtain ed following selection for nearby gene conversions or crossovers among rand om spores. The largest class of events involving the minisatellite was a 3: 1 segregation of parental-size alleles, a class that would have been missed in all previous studies of minisatellites. Comparison of the sequences of the parental and novel alleles revealed that DNA must have been removed fro m the recipient array while a newly synthesized copy of donor array sequenc es was inserted. The length of inserted sequences did not appear to be cons trained by the length of DNA that was removed. In cases where one or both s ides of the insertion could be determined, the insertion endpoints were con sistent with the suggestion that the event was mediated by alignment of hom ologous stretches of donor/recipient DNA.