Hygromycin B resistance as dominant selectable marker in yeast.

Saccharomyces cerevisiae is normally sensitive to the drug hygromycin B; a hygromycin B concentration of 200 µg/ml in agar plates is sufficient to completely inhibit growth. We constructed yeast-E. coli bifunctional plasmids which confer hygromycin B resistance to Saccharomyces cerevisiae. Promoters and amino terminal coding regions of a heat shock gene, a heat shock cognate gene, and the phosphoglycerate kinase gene from yeast were fused to a bacterial hygromycin B resistance gene. In all three cases, yeast cells containing plasmids with the hybrid hygromycin B resistance gene were resistant to high levels of the drug. Yeast cells containing these plasmids can also be directly selected after transformation by using hygromycin B. The intact bacterial hygromycin B resistance gene and the kanamycin resistance gene from Tn903 were also tested in yeast for their ability to confer resistance to hygromycin B and G418. The intact bacterial genes were not effective in conferring drug resistance to yeast cells.