Xyloglucanases: an understudied tool for the enzymatic depolymerization of non-woody lignocellulosics

Xyloglucan is a complex polysaccharide, consisting of both hexoses and pentoses, and is considered a minor hemicellulose, present mainly in primary plant cell walls. Due to the complexity of the polymer, multiple enzymes, acting in synergy, are needed for its complete degradation. Xyloglucan-degrading enzymes have also been shown to act synergistically with enzymes acting on other lignocellulose polymers, since xyloglucan is often found complexed with other polysaccharides in plant cell walls. The present primer article aims at illustrating the literature gaps regarding the enzymology, structural biology, phylogenetics, and biochemistry of xyloglucan-degrading microbial enzymes. Moreover, mapping the synergistic relationships of xyloglucan-degrading enzymes with those acting on other polysaccharides could enable the design of efficient enzyme cocktails for the saccharification and valorization of xyloglucan-containing feedstocks in future biorefineries.