From spores to antibiotics via the cell cycle.

Spore formation in Bacillus subtilis is a superb experimental system with which to study some of the most fundamental problems of cellular development and differentiation. Work begun in the 1980s and ongoing today has led to an impressive understanding of the temporal and spatial regulation of sporulation, and the functions of many of the several hundred genes involved. Early in sporulation the cells divide in an unusual asymmetrical manner, to produce a small prespore cell and a much larger mother cell. Aside from developmental biology, this modified division has turned out to be a powerful system for investigation of cell cycle mechanisms, including the components of the division machine, how the machine is correctly positioned in the cell, and how division is coordinated with replication and segregation of the chromosome. Insights into these fundamental mechanisms have provided opportunities for the discovery and development of novel antibiotics. This review summarizes how the bacterial cell cycle field has developed over the last 20 or so years, focusing on opportunities emerging from the B. subtilis system.