A sudden increase in the growth temperature of Methylophilus methylotrophus results in the synthesis of a number of unique proteins. The major heat-shock proteins have apparent molecular masses of 83, 78, 63, 60, 16 and 14 kDa. Other stress conditions elicit a similar response, although there are significant differences in the sets of proteins produced under the various conditions. Addition of methanol induces proteins identical in size to the heat-shock 83, 79, 63 and 14 kDa proteins and also induces unique 94, 36 and 29 kDa species. Addition of ethanol induces proteins identical in size to the 78 and 20 kDa heat-shock proteins and the 94 and 36 kDa methanol-induced proteins and an apparently unique 13 kDa species. Simultaneous exposure to elevated temperature and either methanol or ethanol resulted in the synthesis of all of the proteins induced by the separate treatments. The stress-shock proteins are differentially located in cytoplasmic, periplasmic and membrane fractions.
