A Tomato Endo-β-1,4-glucanase, SlCel9C1, Represents a Distinct Subclass with a New Family of Carbohydrate Binding Modules (CBM49)

摘要: A critical structural feature of many microbial endo-β-1,4-glucanases (EGases, or cellulases) is a carbohydrate binding module (CBM), which required for effective crystalline cellulose degradation. However, CBMs are absent from plant EGases that have been biochemically characterized to date, and accordingly, not generally thought the capacity degrade cellulose. We report biochemical characterization tomato EGase, Solanum lycopersicum Cel8 (SlCel9C1), with distinct C-terminal noncatalytic represents previously uncharacterized family CBMs. In vitro studies demonstrated this indeed binds can similarly bind as part recombinant chimeric fusion protein containing an EGase catalytic domain bacterium Thermobifida fusca. Site-directed mutagenesis show tryptophans 559 573 play role in binding. The SlCel9C1 CBM, new CBM (CBM49), defining subclass (Class C) EGases, members present throughout kingdom. addition, was shown hydrolyze artificial cellulosic polymers, oligosaccharides, variety cell wall polysaccharides.