title: Two-dimensional reference map of Agrobacterium tumefaciens proteins.
abstract: Proteomics based on two-dimensional (2-D) gel electrophoresis of proteins followed by spot identification with mass spectrometry is a commonly used method for physiological studies. Physiological proteomics requires 2-D reference maps, on which most of the main proteins are identified. We present a reference map for the bacterial plant pathogen Agrobacterium tumefaciens proteins, which contains more than 300 entries with an isoelectric point (pI) between 4 and 7. The quantitative study of the proteins in the analytical window of the master gel demonstrated unique features, in comparison with other bacteria. In addition, a theoretical analysis of several protein parameters was performed and compared with the experimental results. A comparison of the theoretical molecular weight (MW) of the proteins and their theoretical pI with their vertical and horizontal migration distances, respectively, pointed out the existence of several proteins that strongly diverted from the graph trend-line. These proteins were clearly subjected to post-translational modifications, which changed their pI and/or MW. Additional support for post-translational modifications comes from the identification of multiple spots of the same gene products. Post-translational modifications appear to be more common than expected, at least for soluble proteins, as more than 10% of the proteins were associated with multiple spots.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
authors.forename: Ran
authors.initials: R
authors.lastname: Rosen
authors.forename: Ayelet
authors.initials: A
authors.lastname: Sacher
authors.forename: Nelia
authors.initials: N
authors.lastname: Shechter
authors.forename: Dörte
authors.initials: D
authors.lastname: Becher
authors.forename: Knut
authors.initials: K
authors.lastname: Büttner
authors.forename: Dvora
authors.initials: D
authors.lastname: Biran
authors.forename: Michael
authors.initials: M
authors.lastname: Hecker
authors.forename: Eliora Z
authors.initials: EZ
authors.lastname: Ron
mesh_terms: D016960:Agrobacterium tumefaciens / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D007091:Image Processing, Computer-Assisted; D007526:Isoelectric Point; D010449:Peptide Mapping; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins