Open AccessNovel modular enzymes encoded by a cellulase gene cluster in Cellvibrio mixtus
Author(s) -
Centeno Maria S.J.,
Goyal Arun,
Prates José A.M.,
Ferreira Luís M.A.,
Gilbert Harry J.,
Fontes Carlos M.G.A.
Publication year - 2006
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2006.00464.x
Subject(s) - laminarin , biochemistry , glycoside hydrolase , xylanase , cellulase , carbohydrate binding module , cellulosome , gene cluster , enzyme , biology , polysaccharide , cell wall , glucanase , microbiology and biotechnology , chemistry , gene , clostridium thermocellum
Hydrolysis of plant cell wall polysaccharides, a process which is of intrinsic biological and biotechnological importance, requires the concerted action of an extensive repertoire of microbial cellulases and hemicellulases. Here, we report the identification of the gene cluster unk16A, regA and cel5B in the aerobic soil bacterium Cellvibrio mixtus , encoding a family 16 ( Cm Unk16A) glycoside hydrolase (GH), an AraC/XylS transcription activator ( Cm RegA) and a family 5 ( Cm Cel5B) endo‐glucanase, respectively. Cm Unk16A is a modular enzyme comprising, in addition to the catalytic domain, two family 32 carbohydrate‐binding modules (CBMs), termed CBM32‐1 and CBM32‐2, a CBM4 and a domain of unknown function. We show that CBM32‐2 binds weakly to laminarin and pustulan. Cm RegA is also a modular protein containing a highly hydrophobic N‐terminal domain and a C‐terminal DNA‐binding domain of the AraC/XylS family. The role of the identified enzymes in the hydrolysis of cell wall polysaccharides by aerobic bacteria is discussed.