Recombinant expression and inhibition mechanism analysis of pectin methylesterase from Aspergillus flavus.

Phytopathogenic microorganisms can produce pectin methylesterase (PME) to degrade plant cell walls during plant invasion. This enzyme is thought to be a virulence factor of phytopathogens. In this work, PME from Aspergillus flavus (AFPME) was expressed in Pichia pastoris and an in vitro inhibitor study was performed. The purified AFPME with a yield of 52.2% was resolved as one band with a molecular mass of c. 40 kDa by SDS-PAGE. Optimal activity of the enzyme occurred at a temperature of 55 °C and a pH of 4.8. Epigallocatechin gallate (EGCG) strongly inhibited the activity of recombinant AFPME. The molecular docking analysis indicated that EGCG could form hydrogen bonds and π-π interactions with some amino acid residues in the active site of AFPME. Our studies provide a novel strategy for the control of the plant invasion of A. flavus.