A phospho-signaling pathway controls the localization and activity of a protease complex critical for bacterial cell cycle progression.

Temporally and spatially controlled master regulators drive the Caulobacter cell cycle by regulating the expression of >200 genes. Rapid clearance of the master regulator, CtrA, by the ClpXP protease is a critical event that enables the initiation of chromosome replication at specific times in the cell cycle. We show here that a previously unidentified single domain-response regulator, CpdR, when in the unphosphorylated state, binds to ClpXP and, thereby, causes its localization to the cell pole.

MreB actin-mediated segregation of a specific region of a bacterial chromosome.

Faithful chromosome segregation is an essential component of cell division in all organisms. The eukaryotic mitotic machinery uses the cytoskeleton to move specific chromosomal regions. To investigate the potential role of the actin-like MreB protein in bacterial chromosome segregation, we first demonstrate that MreB is the direct target of the small molecule A22.

Oscillating global regulators control the genetic circuit driving a bacterial cell cycle.

A newly identified cell-cycle master regulator protein, GcrA, together with the CtrA master regulator, are key components of a genetic circuit that drives cell-cycle progression and asymmetric polar morphogenesis in Caulobacter crescentus. The circuit drives out-of-phase temporal and spatial oscillation of GcrA and CtrA concentrations, producing time- and space-dependent transcriptional regulation of modular functions that implement cell-cycle processes. The CtrA/GcrA regulatory circuit controls expression of polar differentiation factors and the timing of DNA replication.

DNA methylation affects the cell cycle transcription of the CtrA global regulator in Caulobacter.

The Caulobacter chromosome changes progressively from the fully methylated to the hemimethylated state during DNA replication. These changes in DNA methylation could signal differential binding of regulatory proteins to activate or repress transcription. The gene encoding CtrA, a key cell cycle regulatory protein, is transcribed from two promoters.