A regulatory role for TSL1 on trehalose synthase activity.

UDPG-dependent trehalose synthase activity was determined during growth on glucose medium in controls and yeast strains having deletions on components of the trehalose phosphate synthase complex. Deletion of TPS3 produced any alteration. In contrast, strains harboring deletions tsl1 delta or tsl1 delta/tps3 delta showed no activation of enzyme after glucose exhaustion. To evaluate the role played by TPS3 and TSL1 on trehalose synthase activity we have determined the effect of the addition of a cell free extract from a strain expressing only TPS3 and TSL1 to extracts of strains lacking TSL1, TPS3 or both. No effect was observed on trehalose synthase activity from tps3 delta mutant. The addition of the same extract to trehalose synthase from tsl1 delta or tsl1 delta/tps3 delta strains showed a two-fold activating effect, indicating that TPS3 and TSL1 regulated differently the UDPG-dependent trehalose synthase activity.