HSP104 RESPONDS TO HEAT AND OXIDATIVE STRESS WITH DIFFERENT INTRACELLULAR-LOCALIZATION IN SACCHAROMYCES-CEREVISIAE

TPN (tetrachloroisophthalonitrile) affected the growth in yeast Saccha romyces cerevisiae and enhanced the superoxide dismutase and glutathio ne reductase activity under sublethal concentration. Conversely, mild heat-shock treatment had no effect on the enzyme activities. These sho w they inhibit the metabolism diversely: TPN is an oxidative stressor and mild heat-shock treatment leads to thermogenesis. We have earlier reported that on exposure to TPN under sublethal concentration, heat-s hock protein Hsp104 was induced in the same way as in the mild heat-sh ock treatment (Fujita et al., Biochem. Biophys. Res. Commun. (1995) 21 6, 1041-1047). However, intracellular localizations of Hsp104 showed d ifferent patterns in each treated cell according to immunoelectron mic roscopic observation. While Hsp104 was localized upon the circumferenc e of the protein aggregates in mild heat-shocked cells, Hsp104 was dis tributed over the entire TPN-treated cells with no protein aggregates. These findings suggest Hsp104 adaptively responds to comprehensive st ress and participates in an emergent rescue function as a molecular ch aperone. (C) 1998 Academic Press.