Temporal and spatial regulation in prokaryotic cell cycle progression and development.

Bacteria exhibit a high degree of intracellular organization, both in the timing of essential processes and in the placement of the chromosome, the division site, and individual structural and regulatory proteins. We examine the temporal and spatial regulation of the Caulobacter cell cycle, bacterial chromosome segregation and cytokinesis, and Bacillus subtilis sporulation. Mechanisms that control timing of cell cycle and developmental events include transcriptional cascades, regulated phosphorylation and proteolysis of signal transduction proteins, transient genetic asymmetry, and intercellular communication. Surprisingly, many signal transduction proteins are dynamically localized to specific subcellular addresses during the cell division cycle and sporulation, and proper localization is essential for their function. The Min proteins that govern division site selection in Escherichia coli may be the first example of a system that generates positional information de novo.