YEAST ARTIFICIAL CHROMOSOME FRAGMENTATION VECTORS THAT UTILIZE URA3 SELECTION

Two fragmentation vectors, pSE1 and pSE2, were developed for targeting yeast artificial chromosomes (YACs) containing human genomic DNA. Ura- yeast cells containing YACs were selected with 5-fluoro-orotic acid. Fragmented YACs were subsequently generated by transformation to a Ura+ phenotype. Over 80% of the transformants contained YACs of reduced molecular size. These fragmented YACs will prove to be useful in mapping the region of human chromosomes covered by the parental YAC. Fragmentation utilizing URA3 transformation provides a method for producing YAC deletion sets from YACs contained in AB1380 and other ura3- yeast stains. Linkage of a neomycin resistance gene to the URA3 gene facilitates functional analysis of these YACs in eukaryotic cells.