Unique Distribution of <Emphasis Type="Italic">GAL</Emphasis> Genes on Chromosome XI in the Yeast <Emphasis Type="Italic">Saccharomyces naganishii</Emphasis>

A region of DNA extending from GAL7 to GAL1 was cloned in the yeast Saccharomyces naganishii. Sequence analysis revealed that GAL7 and GAL1 are separated by approximately 2 kbp and share a common promoter region. Although GAL7, GAL10, and GAL1 are clustered in this order in previously studied hemiascomycetous yeasts, GAL10 was not found between GAL7 and GAL1 in S. naganishii. Southern blotting of S. naganishii chromosomal DNA showed that both the GAL7–GAL1 region and GAL10 are located on chromosome XI, but that GAL10 is located more than 10 kbp away from GAL7–GAL1. Thus, S. naganishii and S. cerevisiae, while related phylogenetically, do not share the same orientation with respect to GAL genes. These data are highly relevant to studies of chromosomal evolution in yeast.