Cloning, sequence analysis and overexpression of a Saccharomyces cerevisiae endopolygalacturonase-encoding gene (PGL1)

Only a few yeast strains produce pectin-degrading enzymes such as pectin es terases and depolymerases (hydrolases and lyases). Strain SCPP is the only known Saccharomyces strain to produce these pectinases. One of these pectol ytic enzymes, PGL1-encoded endopolygalacturonase (EC 3.2.1.15), hydrolyses the alpha-1,4-glycosidic bonds within the rhamnogalacturonan chains in pect ic substances. This paper presents the cloning and sequencing of the first S. cerevisiae gene involved in pectin degradation. Few differences were fou nd between the two deduced amino acid sequences encoded by PGL1-1 from a pe ctolytic (PG(+)) strain (SCPP) and PGL1-2 from a non-pectolytic (PG(-)) str ain (X2180-1B). Similarities were found with other polygalacturonases from plants and other microorganisms. Of the two S. cerevisiae genes, only the o ne isolated from strain SCPP was able; by overexpression, to confer endopol ygalacturonase activity to a laboratory strain of S. cerevisiae. Overexpres sion of PGL1-1 gene in a non-pectolytic strain resulted in halo formation o n polygalacturonic acid-containing a,aar plates stained with ruthenium red. Copyright (C) 1999 John Wiley & Sons, Ltd.