5-78: Functional gene cloning and characterization of enzymes targeting α-glucuronic acid linkages in plant cell wall

The genes encoding Schizophyllum commune glucuronoyl esterase (CE15) and Pichia stipitis α-glucuronidase (GH115) were identified in the genomic sequences, chemically synthesized, constitutively expressed and secreted in active form in Pichia pastoris.  The recombinant proteins were individually purified at high yields and characterized with respect to molecular size, pI, N-terminal sequence, catalytic properties, and kinetic parameters.  The CE15 esterase cleaved synthetic substrate mimics of ester bonds between lignin alcohols and glucuronoxylan.  The GH115 α-glucuronidase hydrolyzed MeGlcA linked to internal xylopyranosyl residues of glucuronoxylan.  The role of the two enzymes in microbial plant cell wall degradation and their biotechnological potential are under investigation.