Analysis of the outer membrane proteome of Caulobacter crescentus by two-dimensional electrophoresis and mass spectrometry

Nikhil D. Phadke, Mark P. Molloy, Stephanie A. Steinhoff, Peter J. Ulintz, Philip C. Andrews, Janine R. Maddock*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)


Caulobacter crescentus, a Gram negative α-purple bacterium that displays an invariant asymmetric cell division pattern, has become a key model system for the study of bacterial development. Membrane proteins play key roles in cell cycle events, both as components of landmark morphological structures and as critical elements in regulation of the cell cycle. Recent advances for the isolation and solubilization of bacterial membrane proteins prior to isoelectric focusing have significantly improved the separation of outer membrane proteins by two-dimensional (2-D) electrophoresis. In this work we describe the analysis of the outer membrane proteome of Caulobacter crescentus. Proteins were identified using 2-D gel electrophoresis and peptide mass fingerprinting by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. We identified 54 unique proteins out of which 41 were outer membrane proteins. Of the outer membrane proteins, 16 were identified as TonB-dependent receptor proteins. These studies were executed simultaneously with the Caulobacter genome sequencing project and advantages and limitations of proteomic analysis of a nonannotated genome are discussed. Finally, protein levels between cells grown in rich and minimal media are compared which demonstrates that many of the TonB-dependent receptor proteins are found at higher levels in minimal medium.

Original languageEnglish
Pages (from-to)705-720
Number of pages16
Issue number5
Publication statusPublished - May 2001
Externally publishedYes


  • Caulobacter crescentus
  • Mass spectrometry
  • Membrane proteins
  • Proteome PRO 0065
  • Two-dimensional electrophoresis


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