Levels of Small Molecules and Enzymes in the Mother Cell Compartment and the Forespore of Sporulating Bacillus megaterium

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Abstract
The amounts of a number of small molecules and enzymes in the mother cell compartment and the developing forespore during sporulation of B. megaterium were determined. Significant amounts of ATP and NADH were present in the forespore compartment before accumulation of dipicolinic acid (DPA), but these compounds disappeared as DPA was accumulated. 3-Phosphoglyceric acid (3-PGA) accumulated only within the developing forespore, beginning 1-2 h before DPA accumulation. Throughout its development the forespore contained constant levels of enzymes of 3-PGA synthesis (phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase) and 3-PGA utilization (phosphoglycerate mutase, enolase and pyruvate kinase) at levels similar to those in the mother cell and the dormant spore. Despite the presence of enzymes for 3-PGA utilization, this compound was stable within isolated forespores. Two acid-soluble proteins (A and B proteins) accumulated only in the forespore, beginning 1-2 h before DPA accumulation. At this time the specific protease involved in degradation of the A and B proteins during germination also appeared, but only in the forespore compartment. Nevertheless, the A and B protein were stable within isolated forespores. Arginine and glutamic acid accumulated within the forespore in parallel with DPA accumulation. The forespore also contained the enzyme arginase at a level similar to that in the mother cell and a level of glutamic acid decarboxylase 2 to 25-fold higher than that in the mother cell, depending on when in sporulation the forespores were isolated. The specific activities of several other enzymes (protease active on Hb, ornithine transcarbamylase, malate dehydrogenase, aconitase and isocitrate dehydrogenase) in forespores were about 10% or less of the values in the mother cell. Aminopeptidase was present at similar levels in both compartments; threonine deaminase was not found in either compartment.