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A phosphorelay system controls stalk biogenesis during cell cycle progression in Caulobacter crescentus
Emanuele G Biondi1, Jeffrey M Skerker, Muhammad Arif
1Bauer Center for Genomics Research, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.
Molecular Microbiology
|January 5, 2006
Summary
Researchers discovered a new pathway regulating stalk formation in Caulobacter crescentus. This involves TacA and ShpA working with RpoN (sigma54) to control cell development and gene expression during the cell cycle.
Area of Science:
- Developmental biology
- Microbiology
- Cell biology
Background:
- Cell cycle progression and morphogenesis are tightly coordinated during development.
- Caulobacter crescentus exhibits distinct cell cycle-dependent differentiation into stalked and swarmer cells.
- The alternative sigma factor RpoN (sigma54) is crucial for flagellum and stalk construction.
Purpose of the Study:
- To investigate the molecular mechanisms coordinating cell cycle progression and stalk biogenesis in Caulobacter crescentus.
- To identify novel regulators involved in cell cycle-dependent stalk formation.
- To elucidate the signaling pathway controlling stalk development.
Main Methods:
- Phosphotransfer profiling to identify components of signaling pathways.
- Whole genome microarrays to identify gene regulons.
- Genetic analysis of gene knockouts and their effect on cell morphology.
Main Results:
- A sigma54-dependent activator, TacA, collaborates with RpoN to activate genes for stalk biogenesis.
- The histidine phosphotransferase ShpA is essential for stalk formation.
- A novel phosphorelay pathway from ShkA to ShpA to TacA was identified, activating TacA in vivo.
- The TacA regulon was identified, with StaR shown to regulate stalk length.
Conclusions:
- A novel signaling pathway involving ShkA, ShpA, and TacA regulates cell cycle-dependent stalk biogenesis in Caulobacter crescentus.
- This study establishes a general method for identifying phosphorelay connectivity in two-component signal transduction systems.
- Understanding these pathways provides insights into bacterial development and morphogenesis.
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