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Enrichment of Phosphoproteins and Phosphopeptide Derivatization Identify Universal Stress Proteins in Elicitor-Treated Arabidopsis

October 2008 , Volume 21 , Number  10
Pages  1,275 - 1,284

Marit Lenman, Carolin Sörensson, and Erik Andreasson

Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-223 62 Lund, Sweden

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Accepted 16 June 2008.

Protein phosphorylation is a key biological process that regulates reactions involved in plant-microbe interactions. The phosphorylated form of a protein often represents only a small fraction of the total population and can be problematic to analyze in a mass spectrometer. We demonstrate how a titanium dioxide (TiO2) resin can be employed for the enrichment of phosphoproteins, as well as a method to derivatize TiO2-purified phosphopeptides to facilitate determination of the exact site of phosphorylation. The use of these methods was exemplified by the identification of two plant proteins that were shown to be phosphorylated after the elicitation of Arabidopsis cells with Phytophthora infestans zoospores and xylanase. Both of the proteins that were identified, At5g54430.1 and At4g27320.1, were found to contain a universal stress protein domain with conserved residues for ATP binding.

Additional keywords:4-sulfophenyl isothiocyanate, SPITC.

© 2008 The American Phytopathological Society