The Interaction betweenEndopolygalacturonase fromFusarium moniliformeand PGIP fromPhaseolus vulgarisStudied by Surface Plasmon Resonance and Mass Spectrometry

A combination of surface plasmon resonance (SPR) and matrix-assisted laser-desorptionionization- time-of-flight mass spectrometry (MALDI-TOF-MS) was used to study the interaction betweenendopolygalacturonase (PG) fromFusarium moniliformeand a polygalacturonase-inhibiting protein (PGIP) fromPhaseolus vulgaris.PG hydrolyses the homogalacturonan of the plant cell wall and is considered an important pathogenicity factor of many fungi. PGIP is a specific inhibitor of fungal PGs and is thought to be involved in plant defence against phytopathogenic fungi. SPR was used either to study the effect of the PG glycosylation on the formation of the complex with PGIP, and as a sensitive affinity capture of an interacting peptide from a mixture of PG fragments obtained by limited proteolysis. Mass spectrometry allowed to characterise the interacting peptide eluted from the sensor surface.