Profiling the secretome of the marine bacterium Pseudoalteromonas tunicata using amine-specific isobaric tagging (iTRAQ)

J Proteome Res. 2007 Mar;6(3):967-75. doi: 10.1021/pr060416x.


The eukaryote-associated marine bacterium Pseudoalteromonas tunicata produces a range of target-specific compounds that inhibit different types of marine organisms including invertebrate larvae and algal spores, as well as a broad spectrum of fungi, protozoa, and bacteria. The ability to produce such bioactive compounds is correlated to the expression of a yellow and a purple pigment in P. tunicata. To investigate the regulation and biosynthesis of the pigments and bioactive compounds, the expressed secretome of the pigmented wild-type P. tunicata and a nonpigmented mutant (wmpD-) defective in the type-II secretion pathway were compared. Secreted proteins were digested with trypsin, labeled using amine-specific isobaric tagging reagents (iTRAQ), and identified using two-dimensional SCX and nano C18 RP liquid-chromatography coupled with tandem mass spectrometry (LC/LC-MS/MS). The iTRAQ labeling experiments enabled accurate measurement of the proteins identified in this work. A sequence-base prediction of P. tunicata secretome was also obtained and compared to the expressed proteome to determine the role of the type-II secretion pathway in this bacterium. Our results suggest that this secretion pathway has a role in iron transport and acquisition in P. tunicata.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amines / analysis*
  • Chromatography, Liquid
  • Iron / metabolism
  • Molecular Probes
  • Proteins / analysis*
  • Proteins / metabolism*
  • Proteomics / methods
  • Pseudoalteromonas / chemistry*
  • Tandem Mass Spectrometry
  • Trypsin / metabolism


  • Amines
  • Molecular Probes
  • Proteins
  • Iron
  • Trypsin