α-Galactosidase Aga27A, an Enzymatic Component of theClostridium josuiCellulosome

ABSTRACT The Clostridium josui aga27A gene encodes the cellulosomal α-galactosidase Aga27A, which comprises a catalytic domain of family 27 of glycoside hydrolases and a dockerin domain responsible for cellulosome assembly. The catalytic domain is highly homologous to those of various α-galactosidases of family 27 of glycoside hydrolases from eukaryotic organisms, especially plants. The recombinant Aga27A α-galactosidase devoid of the dockerin domain preferred highly polymeric galactomannan as a substrate to small saccharides such as melibiose and raffinose.