Sequence and functional analysis of a 7.2 kb fragment of Saccharomyces cerevisiae chromosome II including GAL7 and GAL10 and a new essential open reading frame.

The nucleotide sequence of a fragment of 7200 base pairs of Saccharomyces cerevisiae chromosome II has been determined. The sequence contains three open reading frames (ORFs). Two genes for galactose metabolism, GAL7 and part of the GAL10 coding region, are localized on the fragment. Comparison to the previously published sequence data showed several differences, leading to changes in the amino acid sequences of GAL7 and GAL10. One new ORF, YBR0224, was detected, coding for a protein with 918 amino acids. Comparison to the DNA and protein data bases showed no significant homologies. The protein has some interesting features pointing to a function involved in transcription regulation: a leucine zipper motif, a highly acidic region, possibly involved in transcription activation and a putative nuclear localization signal. Deletion analysis showed that the gene is essential when deleted in strain W303. Spores could germinate and form microcolonies, but efforts to propagate the colonies failed. Deletion of this gene in a different genetic background (strain M5) led to very poor-growing mutant strains with cells showing aberrant cellular morphologies.