Effect of erythromycin upon the protein pattern of heat shocked S. cerevisiae : Identification of new classes of heat-shock and heat-stroke products.

Conventional and two dimensional (2D) electrophoresis on ultrathin horizontal slab gels shows that heat shock proteins are synthesized and heat stroke proteins are curtailed after the transfer of Saccharomyces cerevisiae strain Z270 from 23 °C to 37 °C. Upon addition of the mitochondrial translation inhibitor erythromycin to cell cultures which incorporated labelled methionine at 23 °C, and after the transfer to 37 °C, we have shown that: a) in extracts of cells labelled at 23 °C, translational products sensitive to erythromycin could be observed on 2D gels; the synthesis of some of these proteins was enhanced, whereas the synthesis of some others declined when the labelling was carried out 20 min after the transfer to 37 °C; b) there are heat shock proteins whose induction at 37 °C was prevented by erythromycin; c) labelling of a number of proteins became weaker at 37 °C, but not at 23 °C, when this was done in the presence of erythromycin; d) two proteins were detectable only in samples labelled at 37 °C in the presence of erythromycin.