Genetic and physiological regulation of bacterial endospore development.

Bacterial endospores are complex structures residing inside endospore-forming, mainly gram-positive bacteria. The process of sporulation is considered a simple example of cell differentiation. Endospores enable the organism to resist environmental stresses. Sporulation can be divided into several stages, from axial DNA filamentation to mother cell lysis. The structure and formation of an endospore is an attractive model for the assembly of complex macromolecular structures during development. The expression of genes involved in sporulation is compartmentalized and different sets of genes are expressed in the prespore and mother cell, this being associated with the subsequent activation of four sporulation-specific sigma factors. Their synthesis and activity are tightly regulated and the regulatory mechanisms have overlapping roles.