title: Profiling the secretome of the marine bacterium Pseudoalteromonas tunicata using amine-specific isobaric tagging (iTRAQ).
abstract: 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.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, Centre for Marine Biofouling and Bio-Innovation, and Bioanalytical Mass Spectrometry Facility, University of New South Wales, NSW 2052, Australia.
authors.forename: Flavia F
authors.initials: FF
authors.lastname: Evans
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Raftery
authors.forename: Suhelen
authors.initials: S
authors.lastname: Egan
authors.forename: Staffan
authors.initials: S
authors.lastname: Kjelleberg
mesh_terms: D000588:Amines / Q000032:analysis*; D002853:Chromatography, Liquid; D007501:Iron / Q000378:metabolism; D015335:Molecular Probes; D011506:Proteins / Q000032:analysis* / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D031161:Pseudoalteromonas / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014357:Trypsin / Q000378:metabolism
chemical_list: D000588:Amines; D015335:Molecular Probes; D011506:Proteins; D007501:Iron; D014357:Trypsin