Fungal polygalacturonases exhibit different substrate degradation patterns and differ in their susceptibilities to polygalacturonase-inhibiting proteins.
Polygalacturonic acid (PGA) was hydrolyzed by polygalacturonases (PGs) purified from six fungi. The oligogalacturonide products were analyzed by HPAEC-PAD (high performance anion exchange chromatography-pulsed amperimetric detection) to assess their relative amounts and degrees of polymerization. The abilities of the fungal PGs to reduce the viscosity of a solution of PGA were also determined. The potential abilities of four polygalacturonase-inhibiting proteins (PGIPs) from three plant species to inhibit or to modify the hydrolytic activity of the fungal PGs were determined by colorimetric and HPAEC-PAD analyses, respectively. Normalized activities of the different PGs acting upon the same substrate resulted in one of two distinct oligogalacturonide profiles. Viscometric analysis of the effect of PGs on the same substrate also supports two distinct patterns of cleavage. A wide range of susceptibility of the various PGs to inhibition by PGIPs was observed. The four PGs that were inhibited by all PGIPs tested exhibited an endo/exo mode of substrate cleavage, while the three PGs that were resistant to inhibition by one or more of the PGIPs proceed by a classic endo pattern of cleavage.
Cook
B J
BJ
University of Georgia, Athens 30602, USA.
Clay
R P
RP
Bergmann
C W
CW
Albersheim
P
P
Darvill
A G
AG
D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005658:Fungi / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D010368:Pectins / Q000378:metabolism; D010940:Plant Proteins / Q000494:pharmacology; D011096:Polygalacturonase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D009844:Oligosaccharides; C081479:PGIP protein, plant; D010940:Plant Proteins; D010368:Pectins; D011096:Polygalacturonase; C003181:polygalacturonic acid