ppGpp and polyphosphate modulate cell cycle progression in Caulobacter crescentus

J Bacteriol. 2012 Jan;194(1):28-35. doi: 10.1128/JB.05932-11. Epub 2011 Oct 21.


Caulobacter crescentus differentiates from a motile, foraging swarmer cell into a sessile, replication-competent stalked cell during its cell cycle. This developmental transition is inhibited by nutrient deprivation to favor the motile swarmer state. We identify two cell cycle regulatory signals, ppGpp and polyphosphate (polyP), that inhibit the swarmer-to-stalked transition in both complex and glucose-exhausted media, thereby increasing the proportion of swarmer cells in mixed culture. Upon depletion of available carbon, swarmer cells lacking the ability to synthesize ppGpp or polyP improperly initiate chromosome replication, proteolyze the replication inhibitor CtrA, localize the cell fate determinant DivJ, and develop polar stalks. Furthermore, we show that swarmer cells produce more ppGpp than stalked cells upon starvation. These results provide evidence that ppGpp and polyP are cell-type-specific developmental regulators.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Caulobacter crescentus / cytology*
  • Caulobacter crescentus / metabolism*
  • Cell Proliferation
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Bacterial / physiology
  • Glucose / metabolism
  • Guanosine Tetraphosphate / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism
  • Polyphosphates / metabolism*
  • Protein Transport
  • Pyrophosphatases / genetics
  • Pyrophosphatases / metabolism
  • Signal Transduction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • Bacterial Proteins
  • CtrA protein, Caulobacter
  • DNA-Binding Proteins
  • Polyphosphates
  • Transcription Factors
  • Guanosine Tetraphosphate
  • Phosphotransferases (Alcohol Group Acceptor)
  • Pyrophosphatases
  • Glucose