Erwinia pectate lyase differences revealed by action pattern analyses

Abstract Erwinia bacteria cause soft-rot diseases of host plants by secretion of cell wall degrading enzymes, including pectate lyase (PL) isoenzymes. Sequencing of DNA fragments from Erwinia carotovora subsp. atroseptica established the genomic organization of three tandemly arranged pel genes encoding PLs. Expression of the individual genes in Escherichia coli followed by purification of the corresponding recombinant enzymes yielded 7–33 mg PLs (I culture) −1 suitable for kinetic analyses. Apart from their natural substrate pectate, the isoenzymes also degraded 31% and 68% esterified pectins. Although individual PL activities towards 68% esterified pectin were low, the presence of PL3 in enzyme combinations enhanced the activity by up to 64%. Analyses employing high performance anion exchange chromatography confirmed these findings and revealed that particularly pentamers, or heptamers, produced by the actions of PL1 and PL2, were further depolymerized by PL3. In line with this, individual PL isoenzymes were shown to exhibit distinctive action patterns.