Deletion of YHB1. The entire ORF of the YHB1 gene in the haploid yeast strain Y190 was replaced by either hphMX (lanes 1 and 7) or KanMX2 (lanes 2 and 8) cassettes (see Materials and Methods for details). Targeted (lanes 7–10) and wild-type (lanes 1–4) YHB1 fragments in yeast were detected by PCR with specific primer pairs (Hmp1512se/Kanas and Hmp1512se/Hmp1899as, respectively). Lanes 3 and 9, wild-type Y190 cells; lanes 4 and 10, no DNA template controls; lanes 5 and 6, 100-bp and 500-bp DNA size ladders (GIBCO), respectively.