![]() The regulation of events in the mother cell and the forespore is due to the presence of four different sigma factors, two in each compartment, which assures that each genome gives rise to a different set of products (Fig. The mother cell is discarded by lysis after the completion of sporulation. ![]() The forespore ultimately becomes a metabolically quiescent and stress-resistant spore that can give rise to future progeny by germination when conditions improve. The genome of the mother cell provides the components for constructing the spore exterior and the genome of the forespore provides the components for constructing the spore interior. The subsequent engulfment of the prespore by the mother cell compartmentalizes the prespore inside the mother cell (Fig. The initiation of sporulation by the formation of a polar septum instead of the vegetative midcell septum requires the accumulation of a sufficient concentration of SpoOA~P. The integration of the extracellular and intracellular signals is regulated through a multicomponent phosphorelay that controls the prosphorylation of the transcriptional regulator SpoOA. Before initiating sporulation, cells monitor many intracellular factors, such as DNA replication and the TCA cycle. However, if cells are at a low density, the chances of finding additional nutrients is higher and sporulation less desirable. It may be that if starving cells are at a high density, it is better to sporulate rather than compete for nutrients. Cell density is also important for efficient sporulation, presumably to ensure that cells are sufficiently abundant. ![]() The primary signal for the initiaton of sporulation is nutrient starvation. Endospore formation has been found exclusively in gram-positive bacteria and is best understood in Bacillus subtilis.
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