Heterologous expression and characterization of the endocellulase encoding gene cel3A from the basidiomycete Polyporus arcularius

The genomic and cDNA clones encoding the carboxymethyl cellulase (CMCase) gene (cel3A) of Polyporus arcularius were sequenced and characterized. The coding region of cel3A, composed of 1329 bp, was found to encode a polypeptide of 243 amino acids that has similarity with FI-CMCase of Aspergillus aculeatus. Expression of the cel3A cDNA in Escherichia coli led to production of a nonglycosylated protein as an active form; moreover, CMCase activity measured by the viscometric method was enhanced 4.47 times by addition of cellobiose. These results indicate that glycosylation and any modification of protein such as processing are not required for Cel3A activity.