Molecular biology, genomics and bioinformatics insights into fungal pectin lyase: An overview

Pectinase represents an industrially important group of enzymes, comprising pectin lyases (PNL), pectate lyases (PL), polygalacturonases (PG), and pectin methylesterases (PME) as a well-studied member with diverse applications. Among pectinases, pectin lyase occupies unique positions based on its reaction mechanisms. Pectin lyase is associated with degradation of pectin polymer directly by b-elimination, and 4, 5-unsaturated oligogalacturonide is the product formed. In case of other pectinases, sequential degradation of pectin molecule occurs. Further, its relevance in fruit juice clarification is mainly because of two reasons. First, they are known to degrade pectin without altering the ester group responsible for the specific aroma of the juice and second, the highly toxic methanol is not generated by the process of degradation of pectin-by-pectin lyases. The applications of pectin lyases in retting processes have recently been elucidated. There exist substantial reports of fungal pectin lyases especially from Aspergillus and Penicillium species, with sole emphasis on production optimization, purification, and biochemical characterizations. As far as molecular biology of pectin lyases is concerned, few studies have been performed especially on Aspergillus species and molecular cloning and expression of relevant pectin lyases genes have been reported. Efforts have been made to decipher the factors influencing pectinases gene regulation, though not extensively. Molecular cloning of pectin lyase gene from diverse sources, its manipulation by using directed evolution techniques, and searching for novel sources by utilizing metagenomic-based approach are some of the recent developments in pectin lyase research, which is a subject matter for the present review.