TREHALOSE-6-P SYNTHASE IS DISPENSABLE FOR GROWTH ON GLUCOSE BUT NOT FOR SPORE GERMINATION IN SCHIZOSACCHAROMYCES-POMBE

Trehalose-6-P inhibits hexokinases in Saccharomyces cerevisiae (M. A. Blazquez, R. Lagunas, C. Gancedo, and J. M. Gancedo FEBS Lett. 329:51- 54, 1993), and disruption of the TPS1 gene (formerly named CIF1 or FDP 1) encoding trehalose-6-P synthase prevents growth in glucose. We have found that the hexokinase from Schizosaccharomyces pombe is not inhib ited by trehalose-6-P even at a concentration of 3 mM. The highest int ernal concentration of trehalose-6-P that we measured in S. pombe was 0.75 mM after heat shock. We have isolated from S. pombe the tps1(+) g ene, which is homologous to the Saccharomyces cerevisiae TPS1 gene. Th e DNA sequence from tps1(+) predicts a protein of 479 amino acids with 65% identity with the protein of S. cerevisiae. The tps1(+) gene expr essed from its own promoter could complement the lack of trehalose-6-P synthase in S. cerevisiae tps1 mutants. The TPS1 gene from S. cerevis iae could also restore trehalose synthesis in S. pombe tps1 mutants. A chromosomal disruption of the tps1(+) gene in S. pome did not have a noticeable effect on growth in glucose, in contrast with the disruptio n of TPS1 in S. cerevisiae. However, the disruption prevented germinat ion of spores carrying it. The level of an RNA hybridizing with an int ernal probe of the tps1(+) gene reached a maximum after 20 min of heat shock treatment. The results presented support the idea that trehalos e-6-P plays a role in the control of glycolysis in S. cerevisiae but n ot in S. pombe and show that the trehalose pathway has different roles in the two yeast species.