Biochemical Characterization of a Pectate Lyase AnPL9 from Aspergillus nidulans

Pectinolytic enzymes have diverse industrial applications. Among these, pectate lyases act on the internal alpha-1,4-linkage of the pectate backbone, playing a critical role in pectin degradation. While most pectate lyases characterized thus far are of bacterial origin, fungi can also be excellent sources of pectinolytic enzymes. In this study, we performed biochemical characterization of the pectate lyase AnPL9 belonging to the polysaccharide lyase family 9 (PL9) from the filamentous fungus Aspergillus nidulans. Recombinant AnPL9 was produced using a Pichia pastoris expression system and purified. AnPL9 exhibited high activity on homogalacturonan (HG), pectin from citrus peel, pectin from apple, and the HG region in rhamnogalacturonan-I. Although digalacturonic acid and trigalacturonic acid were not degraded by AnPL9, tetragalacturonic acid was converted to 4,5-unsaturated digalacturonic acid and digalacturonic acid. These results indicate that AnPL9 degrades HG oligosaccharides with a degree of polymerization > 4. Furthermore, AnPL9 was stable within a neutral-to-alkaline pH range (pH 6.0-11.0). Our findings suggest that AnPL9 is a candidate pectate lyase for biotechnological applications in the food, paper, and textile industries. This is the first report on a fungal pectate lyase belonging to the PL9 family.

Automated summary

Pectinolytic enzymes, including pectate lyases, have diverse industrial applications. In this study, the biochemical characterization of the pectate lyase AnPL9 from the filamentous fungus Aspergillus nidulans was performed. AnPL9 exhibited high activity on various pectin substrates and showed stability within a neutral-to-alkaline pH range. These findings suggest that AnPL9 has potential biotechnological applications in the food, paper, and textile industries.