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Molecular mechanisms of plant cell wall hydrolysis: developing novel biotechnological applications for carbohydrate-binding modules

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Resumo:Xyloglucan (XG) is the major plant cell wall hemicellulose. Biochemical and structural studies on a xyloglucanase, Xgh74A, from Clostridium thermocellum are presented here. In addition, the carbohydrate-binding modules (CBMs) from C. thermocellum Cel9D-Cel44A, CtCBM30 and CtCBM44, which recognize XG, are characterized in this work. CtCel9D-Cel44A’s C-terminal module of unknown function is a CBM, constituting the founder member of family 44. Structural studies revealed that both CtCBM30 and CtCBM44 present Type B binding site topologies where tryptophans play an important role in ligand recognition. Cel44A is an endoglucanase domain displaying some xylanase activity, which action is potentiated by CtCBM44 through a targeting effect. Biochemical and structural studies on CtLic26A-Cel5E are also described here. CtLic26A is a mixed b-1,4-b-1,3-glucanase and Cel5E an endo-b-1,4- glucanase. The three-dimensional structure of CtLic26A provides insights in the mechanism of lichenan recognition by family 26 glycoside hydrolases. Finally, novel biotechnological applications for CBMs were investigated. An experiment was conducted where a barley-based diet for broilers was supplemented with CtLic26ACel5 derivatives, with or without CtCBM11, and with a commercial enzyme. The fusion of four antimicrobial peptides with CipA from CtCBM3 originated recombinants with high affinity for crystalline cellulose, indicating CBMs could fix bioactive molecules to cellulose.
Autores principais:Guerreiro, Catarina Isabel Proença Duarte
Assunto:Clostridium thermocellum Glycoside hydrolases Carbohydrate-binding modules Poultry Antimicrobial peptides Biotechnology Glicósido hidrolases Módulos de ligação a carbohidratos Frangos de carne Péptidos antimicrobianos Biotecnologia
Ano:2008
País:Portugal
Tipo de documento:tese de doutoramento
Tipo de acesso:acesso aberto
Instituição associada:Universidade de Lisboa
Idioma:português
Origem:Repositório da Universidade de Lisboa

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