ISOLATION AND EXPRESSION OF THE GENE WHICH ENCODES A NOVEL ENZYME WITH POLYMETHOXYGALACTURONATE-DEGRADING ACTIVITY IN TRICHOSPORON PENICILLATUM

The novel gene named PSX1, encoding a new protopectinase with the poly methoxygalacturonase activity, was isolated from Trichosporon penicill atum. Nucleotide sequencing revealed that the PSX1 gene is composed of 1080 bases (360 amino acids, 38 747 Da). The N-terminal amino acid se quences of the open reading frame correspond to a signal peptide and p ropeptide processed by a Kex2-like proteinase. Mature PPase SX1 was co mposed of 334 amino acids (36121 Da). PPase SX1 produced by a S. cerev isiae transformant harbouring the PSX1 gene degraded methoxylated poly galacturonic acid as a substrate, but not degraded unmethoxylated poly galacturonic acid. (C) 1997 Federation of European Biochemical Societi es.