A two-dimensional protein gel electrophoresis study of the heat stress response of Bacillus subtilis cells during sporulation

The heat resistance of spores of Bacillus subtilis formed at 30 degrees C w as enhanced by pretreatment at 48 degrees C for 30 min, 60 min into sporula tion, for all four strains examined. sigh-resolution two-dimensional gel el ectrophoresis showed the generation and/or overexpression of 60 proteins, 1 1 of which were specific to heat shock, concurrent to this acquired thermot olerance, The greatest number of new proteins was observed between 30 and 6 0 min after heat shock and the longer the time between exponential growth a nd heat treatment, the fewer differences were observed on corresponding pro tein profiles. The time at which heating produced the maximum increase in s pore resistance and the most new proteins: on two-dimensional gels occurred before alkaline phosphatase and dipicolinic acid production and correspond ed to stage I or II of sporulation. The stress proteins formed disappeared later in sporulation, suggesting that heat shock proteins increase spore he at resistance by altering spore structure rather than by repairing heat dam age during germination and outgrowth.