CLONING, MOLECULAR CHARACTERIZATION, AND EXPRESSION OF AN ENDO-POLYGALACTURONASE-ENCODING GENE FROM SACCHAROMYCES-CEREVISIAE IM1-8B

A structural polygalacturonase-encoding gene (PGU1) from Saccharomyces cerevisiae IM1-8b was cloned and sequenced. The predicted protein com prises 361 amino acids, with a signal peptide between residues 1 and 1 8 and two potential glycosylation points in residues 318 and 330. The putative active site is a conserved histidine in position 222. This po lygalacturonase showed 54% homology with the fungal ones and only 24% homology with their plant and bacterial counterparts. The gene is pres ent in a single gene copy per haploid genome and it is detected in all strains, regardless of their phenotype. The expression of PGU1 gene i n several strains of S. cerevisiae revealed that the polygalacturonase activity depended on the plasmid used and also on the genetic backgro und of each strain but in all cases the enzymatic activity increased. (C) 1998 Federation of European Microbiological Societies. Published b y Elsevier Science B.V. All rights reserved.