Extracellular proteolytic cascade in tomato activates immune protease Rcr3.

Proteolytic cascades regulate immunity and development in animals, but these cascades in plants have not yet been reported. Here we report that the extracellular immune protease Rcr3 of tomato is activated by P69B and other subtilases (SBTs), revealing a proteolytic cascade regulating extracellular immunity in solanaceous plants. Rcr3 is a secreted papain-like Cys protease (PLCP) of tomato that acts both in basal resistance against late blight disease () and in gene-for-gene resistance against the fungal pathogen syn.

Inhibitor Discovery by Convolution ABPP.

Activity-based protein profiling (ABPP) has emerged as a powerful proteomic approach to study the active proteins in their native environment by using chemical probes that label active site residues in proteins. Traditionally, ABPP is classified as either comparative or competitive ABPP. In this protocol, we describe a simple method called convolution ABPP, which takes benefit from both the competitive and comparative ABPP.

Screen of Non-annotated Small Secreted Proteins of Pseudomonas syringae Reveals a Virulence Factor That Inhibits Tomato Immune Proteases.

Pseudomonas syringae pv. tomato DC3000 (PtoDC3000) is an extracellular model plant pathogen, yet its potential to produce secreted effectors that manipulate the apoplast has been under investigated. Here we identified 131 candidate small, secreted, non-annotated proteins from the PtoDC3000 genome, most of which are common to Pseudomonas species and potentially expressed during apoplastic colonization.

Broad-range glycosidase activity profiling.

Plants produce hundreds of glycosidases. Despite their importance in cell wall (re)modeling, protein and lipid modification, and metabolite conversion, very little is known of this large class of glycolytic enzymes, partly because of their post-translational regulation and their elusive substrates. Here, we applied activity-based glycosidase profiling using cell-permeable small molecular probes that react covalently with the active site nucleophile of retaining glycosidases in an activity-dependent manner.

DIGE-ABPP by click chemistry: pairwise comparison of serine hydrolase activities from the apoplast of infected plants.

Activity-based protein profiling (ABPP) is a targeted functional proteomics method that displays the active proteome by using small molecule probes that react covalently with the active sites of protein classes. Comparison of activity profiles from two different samples is not always easy, especially when using probes that generate too many signals. For accurate comparison of protein activities between two proteomes, we developed difference gel electrophoresis ABPP (DIGE-ABPP), which compares two fluorescently labeled proteomes in the same gel lane.