tailieunhanh - Báo cáo khoa học: Crystal structure of a glycoside hydrolase family 6 enzyme, CcCel6C, a cellulase constitutively produced by Coprinopsis cinerea

The basidiomyceteCoprinopsis cinereaproduces the glycoside hydrolase family 6 enzyme CcCel6C at low and constitutive levels. CcCel6C exhibits unusual cellobiohydrolase activity; it hydrolyses carboxymethyl cellulose, which is a poor substrate for typical cellobiohydrolases. Here, we deter-mined the crystal structures of CcCel6C unbound and in complex with p-nitrophenyl b-d-cellotrioside and cellobiose. | Crystal structure of a glycoside hydrolase family 6 enzyme CcCel6C a cellulase constitutively produced by Coprinopsis cinerea 112 2 3 Yuan Liu Makoto Yoshida Yuma Kurakata Takatsugu Miyazaki Kiyohiko Igarashi Masahiro Samejima3 Kiyoharu Fukuda1 Atsushi Nishikawa2 and Takashi Tonozuka2 1 Department of Environmentaland NaturalResource Science Tokyo University of Agriculture and Technology Japan 2 Department of Applied BiologicalScience Tokyo University of Agriculture and Technology Japan 3 Department of BiomaterialSciences Graduate Schoolof Agriculturaland Life Sciences University of Tokyo Japan Keywords basidiomycete cellobiohydrolase cellulase induction endoglucanase glycoside hydrolase family 6 Correspondence T. Tonozuka Department of Applied BiologicalScience Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho Fuchu Tokyo 183-8509 Japan Fax 81 42 367 5705 Tel 81 42 367 5702 E-mail tonozuka@ Received 18 November 2009 revised 4 January 2010 accepted 14 January 2010 doi The basidiomycete Coprinopsis cinerea produces the glycoside hydrolase family 6 enzyme CcCel6C at low and constitutive levels. CcCel6C exhibits unusual cellobiohydrolase activity it hydrolyses carboxymethyl cellulose which is a poor substrate for typical cellobiohydrolases. Here we determined the crystal structures of CcCel6C unbound and in complex with p-nitrophenyl P-D-cellotrioside and cellobiose. CcCel6C consists of a distorted seven-stranded p a barrel and has an enclosed tunnel which is observed in other cellobiohydrolases from ascomecetes Hypocrea jecorina HjeCel6A and Humicola insolens HinCel6A . In HjeCel6A and HinCel6A ligand binding produces a conformational change that narrows this tunnel. In contrast the tunnel remains wide in CcCel6C and the conformational change appears to be less favourable than in HjeCel6A and HinCel6A. The ligand binding cleft for subsite -3 of CcCel6C is also wide and is rather similar to that of .