title: Shotgun proteomic analysis of a chromatophore-enriched preparation from the purple phototrophic bacterium Rhodopseudomonas palustris.
abstract: A proteomics approach was evaluated for analysis of photosyntheis-related proteins that are characteristic of chromatophores, particles derived from purple phototrophic bacterial intracytoplasmic membranes. Proteins of purified chromatophores from Rhodopseudomonas palustris were solubilized and digested with trypsin, to create a collection of peptides that were fractionated by liquid chromatography. Peptide sequences were determined and assigned to specific proteins by analysis of tandem mass spectra of peptides, and comparison to a library derived from the recently determined R. palustris genome sequence. A total of 300 proteins were detected with a probability value >/=0.9, and the number of proteins detected increased to 345 when the minimum probability value was reduced to 0.5. Membrane-integral proteins of the reaction center, cytochrome b/c (1), light-harvesting and ATPase complexes were used as controls to assess how well this approach performs with hydrophobic proteins. New genes were identified, and tentatively designated as encoding photosynthesis-related proteins. We conclude that this approach is a powerful method to evaluate the possible existence of new photosynthesis-related proteins (and genes), although alternative methods are needed to evaluate the exact functions of newly discovered genes.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Fejes
authors.forename: Eugene C
authors.initials: EC
authors.lastname: Yi
authors.forename: David R
authors.initials: DR
authors.lastname: Goodlett
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Beatty