nmt2 of fission yeast: A second thiamine‐repressible gene co‐ordinately regulated with nmt1

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Abstract
We previously described a screen for thiamine‐repressible genes in Schizosaccharomyces pombe and reported on one such gene, nmt1, required for thiamine biosynthesis. Here we describe a second gene, nmt2, recovered in the same screen. Disruption of nmt2 also resulted in thiamine auxotrophy, indicating a role for the nmt2 gene product in thiamine biosynthesis. Both genes are highly transcribed in minimal medium and repressed in medium containing thiamine, and nuclear ‘run‐on’ experiments confirm that expression in both cases is controlled by the rate of transcription initiation. The virtually identical kinetics of induction and repression suggest that the two genes are co‐ordinately regulated. Sequence comparison of the two promoters reveals a canonical TATA box, downstream of which is a perfectly conserved 11 bp element. Transcript mapping experiments show that transcription initiation of both genes is centred on this element.