Cloning and transcript analysis of multiple genes encoding the glycoside hydrolase family 6 enzyme from Coprinopsis cinerea

We searched the genome database of the basidiomycete Coprinopsis cinerea (Coprinus cinereus) and found five genes encoding the glycoside hydrolase family 6 (GH6) enzyme, CcCel6A, CcCel6B, CcCel6C, CcCel6D, and CcCel6E, designated in order of increasing locus number (CC1G-01107.1, CC1G-04166.1, CC1G-08276.1, CC1G-08277.1, and CC1G-10605.1). The amino acid sequence of CcCel6A suggests a two-domain structure consisting of an N-terminal family 1 carbohydrate-binding module (CBM1) and a GH6 catalytic domain, while the other genes lack CBM1. The transcripts of CcCel6A were observed at the active growth stage in cellulose culture, whereas they were absent from glucose culture. Cellobiose strongly induced transcription of CcCel6A. On the other hand, transcripts of CcCel6B, -D, and -E were detected in both glucose and cellulose cultures, and transcription of them was induced weakly by cellobiose. The transcript level of CcCel6C was not influenced by glucose or cellobiose.