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Coat synthesis and spore maturation (Stages V – VI) |
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6. Coat synthesis and spore maturation (Stages V – VI)
Late-stage sporulation comprises events directed towards spore morphogenesis and eventual release of the mature spore by lysis of the mother cell. The regulatory pathways activated during previous stages III and IV are still present in both compartments of the cell. In the forespore specifically, gene transcription drives the production of proteins involved in protection of DNA 160 and germination 161, 160. The spore core is dehydrated and most of its water content is replaced by dipicolinic acid (DPA), which is chelated to calcium ions. DPA is produced in large amounts in the mother cell and transported into the forespore. Synthesis of cortex and coat proteins in both compartments results in further development of protective layers around the spore in the form of a thick peptidoglycan cortex layer and several coat layers. Details on spore coat and cortex assembly and structure are described in recent publications 141, 163, 164, 165.