Mjf. Sarabia et al., THE CELL-CYCLE GENES CDC22-POMBE ENCODE THE LARGE AND SMALL SUBUNITS OF RIBONUCLEOTIDE REDUCTASE( AND SUC22+ OF THE FISSION YEAST SCHIZOSACCHAROMYCES), MGG. Molecular & general genetics, 238(1-2), 1993, pp. 241-251
The cdc22+ gene of Schizosaccharomyces pombe is required early in the
cell cycle, and its transcript varies in concentration in step with th
e cell cycle, with a peak level at the G1-S boundary. The sequences of
the cdc22+ gene and of a multicopy suppressor of cdc22ts mutations, s
uc22+, have been determined. The cdc22+ open reading frame, which is i
nterrupted in the genome by a single intron very close to its 5' end,
encodes a protein of 811 amino acids, which has an amino acid sequence
highly similar to that of the large subunit of ribonucleotide reducta
se from several species. The suc22+ gene contains an uninterrupted ope
n reading frame of 391 amino acids, very similar to the sequence of th
e small subunit of ribonucleotide reductase. Disruption of either gene
is lethal. Upstream of the cdc22+ coding region are seven short seque
nce elements similar to the recognition sequence for MluI, which are i
nvolved in regulating periodic transcription of the gene. Inhibition o
f DNA synthesis by hydroxyurea results in a several-fold increase in t
he level of the cdc22+ transcript. In contrast, hydroxyurea does not i
nduce the 1.5 kb transcript of suc22+, but results in the induction of
a 1.9 kb mRNA which hybridises to suc22+ DNA.