REEXAMINATION OF THE NUCLEOTIDE-SEQUENCE OF GTS1, A CANDIDATE CLOCK-RELATED GENE OF SACCHAROMYCES-CEREVISIAE

We reported that the nucleotide sequence of GTS1, which contains a Gly -Thr repeat shared by the clock-genes of period of Drosophila melanoga ster and frequency of Neurospora crassa, affects the timing of budding and cell size of the yeast Saccharomyces cerevisiae in a gene-dosage dependent manner. A conflicting sequence of GTS1 named LSR1, was found by other investigators, in which one thymidine residue (T) at either nucleotide positions 1879 or 1880 in our sequence was deleted resultin g in reading a Gln-Ala repeat instead of the Gly-Thr repeat. To determ ine which sequence Is correct, we again sequenced the fragments contai ning the particular region using an automated DNA sequencer but failed to determine the sequence due to base-compression of the particular s ite. We analyzed the amino acid composition of the bacterially express ed protein directed by GTS1 and found that it is more similar to the p redicted composition of Lsr1p than to that of Gts1p. Furthermore, the recombinant protein Lsr1p-beta-galactosidase expressed in yeast had en zyme activity but Gts1p-beta-galactosidase did not. Thus, we concluded that GTS1 does not contain a thymidine residue at either positions 18 79 or 1880, that it encodes a protein consisting of 396 amino acid res idues, which is shorter by 21 residues than the sequence we published before, and that it contains a Gln-Ala, instead of a Gly-Thr repeat.