Molecular cloning of chromosome I DNA from Saccharomyces cerevisiae: Isolation of the ADE1 gene

The ADE1 gene of Saccharomyces cerevisiae was isolated by complementation in S. cerevisiae from a yeast genomic DNA library carried on plasmid YEp13. Electron microscopy of R-loop-containing DNA indicated the location of the ADE1 gene on the plasmid insert. Gene disruption and gene replacement were used to demonstrate that the ade1-complementing sequence was the actual ADE1 gene that maps on chromosome I. adel strains which normally form red colonies form white ones when transformed with the cloned ADE1 gene. This property should be very useful, since it enables detection of plasmids carrying this gene under nonselective conditions.