The effect of glycosylation of Endopolygalacturonases and polygalacturonase inhibiting proteins on the production of oligogalacturonides

Abstract

Abstract Fungal endopolygalacturonases (EPGs) are considered to be major pathogenicity factors, facilitating the breakdown of the plant cell wall and releasing biologically active oligogalacturonide elicitors which are also substrates for EPG. The inhibition of EPGs by plant polygalacturonase inhibiting proteins (PGIPs) has led to the hypothesis of PGIPs as general defense factors as a consequence of their proposed role in increasing the lifetime of elicitor active oligogalacturonides. Plant PGIPs exist in a variety of glycoforms in which the peptide backbone is conserved with differing degrees of glycosylation. the population of the glycoforms change depending on the species, cultivar, and tissue investigated. Fungal EPGs also exist in a variety of glycoforms, which resulted in us studying the possible role that the glycosylation of EPG and PGIP may play in affecting the production of biologically active oligogalacturonides via their action on pectic substrates. Using HPAEC-PAD, we studied the oligogalacturonide products formed by the interaction of a variety of glycoforms of EPGs and PGIPs on polygalacturonic acid, allowing us to determine the effect of glycosylation on the sizes or lifetimes of the oligogalacturonides produced.