A soluble protein is immobile in dormant spores of Bacillus subtilis but is mobile in germinated spores:: Implications for spore dormancy

Fluorescence redistribution after photobleaching has been used to show that a cytoplasmic GFP fusion is immobile in dormant spores of Bacillus subtilis but becomes freely mobile in germinated spores in which cytoplasmic water content has increased approximate to2-fold. The GFP immobility in dormant spores. is not due to the high levels of dipicolinic acid in the spore cytoplasm, because GFP was also immobile in germinated cwID spores that had excreted their dipicolinic acid but where cytoplasmic water content had only increased to a level similar to that in dormant spores of several other Bacillus species. The immobility of a normally mobile protein in dormant wild-type spores and germinated cwID spores is consistent with the lack of metabolism and enzymatic activity in these spores and suggests that protein immobility, presumably due to low water content, is a major reason for the metabolic dormancy of spores of Bacillus species.