Proteomic analysis of the bacterial cell cycle

A global approach was used to analyze protein synthesis and stability durin g the cell cycle of the bacterium Caulobacter crescentus. Approximately one -fourth (979) of the estimated C. crescentus gene products were detected by two-dimensional gel electrophoresis, 144 of which showed differential cell cycle expression patterns. Eighty-one of these proteins were identified by mass spectrometry and were assigned to a wide variety of functional groups . Pattern analysis revealed that coexpression groups were functionally clus tered. A total of 48 proteins were rapidly degraded in the course of one ce ll cycle. More than half of these unstable proteins were also found to be s ynthesized in a cell cycle-dependent manner, establishing a strong correlat ion between rapid protein turnover and the periodicity of the bacterial cel l cycle. This is, to our knowledge, the first evidence for a global role of proteolysis in bacterial cell cycle control.