ACETYL XYLAN ESTERASE-II FROM PENICILLIUM-PURPUROGENUM IS SIMILAR TO AN ESTERASE FROM TRICHODERMA-RESSEI BUT LACKS A CELLULOSE-BINDING DOMAIN

Penicillium purpurogenum produces at least two acetyl xylan esterases (AXE I and LI). The AXE II cDNA, genomic DNA and mature protein sequen ces were determined and show that the axe 2 gene contains two introns, that the primary translation product has a signal peptide of 27 resid ues, and that the mature protein has 207 residues, The sequence is sim ilar to the catalytic domain of AXE I from Trichoderma reesei (67% res idue identity) and putative active site residues are conserved, but th e Penicillium enzyme lacks the linker and cellulose binding domain, th us explaining why it does not bind cellulose in contrast to the Tricod erma enzyme. These results point to a possible common ancestor gene fo r the active site domain, while the linker and the binding domain may have been added to the Trichoderma esterase by gene fusion. (C) 1998 F ederation of European Biochemical Societies.