Identification and localization of the major proteins degraded during germination of Bacillus megaterium spores.

Of the 15 to 20% of total spore protein which is degraded during germination of spores of Bacillus megaterium, greater than 80% is derived from a protein fraction soluble in dilute acids such as acetic acid that contains two major proteins, termed A and B. These two proteins are low or absent in germinated spores, log phase cells, and early stationary phase cells, but both are synthesized and appear in parallel late in sporulation after the appearance of nonrefractile forespores but before the appearance of refractile spores. These proteins accumulate during the time that the developing spore becomes resistant to ultraviolet light but well before acquisition of heat resistance. Both proteins are located in the core of the dormant spore, but analysis of ruptured spores has revealed no binding of protein A or B to ribosomes, membranes, or DNA.