Cellulose-Binding Domains: Tools for Innovation in Cellulosic Fiber Production and Modification

Abstract

Plant cell walls are composed of cellulose, nature's most abundant macromolecule, and therefore represent a renewable resource of special technical importance. Cellulose degrading enzymes involved in plant cell wall loosening (expansins), or produced by plant pathogenic microorganisms (cellulases), share similarities favouring the degradation of this highly crystalline substrate. Most of the cellulases and cell wall loosening expansins share a multi-domain structure, which includes a cellulose-binding domain (CBD). CBDs possess the intrinsic ability to strongly and specifically bind to cellulose. CBDs may be applied to engineer hybrid enzymes able to bind to cellulose on one end, and to display enzymatic or chemical reactivity on the other, providing innovative solutions to modify cellulosic surfaces or to immobilise biocatalysts on it. In transgenic plants, CBDs influence polysaccharide synthesis and their assembly in the cell wall. Therefore, CBDs represent biotechnological tools to modify cellulosic fibres either during their growth or during post harvest processing. Plant cell walls are composed of cellulose, nature's most abundant macromolecule, and therefore represent a renewable resource of special technical importance. Cellulose degrading enzymes involved in plant cell wall loosening (expansins), or produced by plant pathogenic microorganisms (cellulases), share similarities favouring the degradation of this highly crystalline substrate. Most of the cellulases and cell wall loosening expansins share a multi-domain structure, which includes a cellulose-binding domain (CBD). CBDs possess the intrinsic ability to strongly and specifically bind to cellulose. CBDs may be applied to engineer hybrid enzymes able to bind to cellulose on one end, and to display enzymatic or chemical reactivity on the other, providing innovative solutions to modify cellulosic surfaces or to immobilise biocatalysts on it. In transgenic plants, CBDs influence polysaccharide synthesis and their assembly in the cell wall. Therefore, CBDs represent biotechnological tools to modify cellulosic fibres either during their growth or during post harvest processing.