Fig. 4.

The C. albicans KAR2 gene can serve as the sole copy of this essential gene in S. cerevisiae. Hemizygous diploid S. cerevisiae strain YJ034W BY4743, which has one copy of the ScKAR2 gene disrupted and one wild-type ScKAR2 gene, was transformed with plasmid pCaKAR2-BX containing the C. albicans KAR2 gene. The cells were then sporulated, and the four spores were dissected from each tetrad on YPD plates and incubated for ~72 h at 30°C (a). Three typical dissected tetrads are shown (A–C). The four spores from each tetrad resulted in normal sized colonies (1–4). To show that two of the spores from the tetrads lack the S. cerevisiae KAR2 gene, colonies from all four spores of one tetrad were streaked onto a SC-URA plate (b) as well as a YPD plate supplemented with 100 µg/mL G418 (c) and grown at 30°C for ~48 h. Lysates were made from cells derived from each spore, and the proteins were analyzed by western blot using antibodies generated against the S. cerevisiae Kar2 and Sec61 proteins (d)