Purification, identification and molecular cloning of glycoside hydrolase family 15 glucoamylase from the brown-rot basidiomycete Fomitopsis palustris.

The brown-rot basidiomycete Fomitopsis palustris produces a major extracellular enzyme of 72 kDa when the fungus is incubated in cellulose culture with 0.2% cellobiose. This protein was purified by column chromatography, and the amino acid sequences of its proteolytic fragments were analyzed. The N-terminal amino acid sequence of one of the fragments showed high identity with fungal glycoside hydrolase family 15 glucoamylases. As its kinetic efficiency increased in proportion to the degree of polymerization of the substrate, the protein was identified as a glucoamylase. A cDNA encoding the glucoamylase (gla) was cloned by reverse transcriptase PCR.