The Glycoside Hydrolase Family 35 β-galactosidase from Trichoderma reesei debranches xyloglucan oligosaccharides from tamarind and jatoba

Trichoderma reesei (anamorph Hypocrea jecorina) produces an extracellular beta-galactosidase from Glycoside Hydrolase Family 35 (TrBga1). Hydrolysis of xyloglucan oligosaccharides (XGOs) by TrBga1 has been studied by hydrolysis profile analysis of both tamarind (Tamarindus indica) and jatoba (Hymenaea courbaril) seed storage xyloglucans using PACE and MALDI-ToF-MS for separation, quantification and identification of the hydrolysis products. The TrBga1 substrate preference for galactosylated oligosac-charides from both the XXXG-and XXXXG-series of jatoba xyloglucan showed that the doubly gal-actosylated oligosaccharides were the first to be hydrolyzed. Furthermore, the TrBga1 showed more efficient hydrolysis against non-reducing end dexylosylated oligosaccharides (GLXG/GXLG and GLLG). This preference may play a key role in xyloglucan degradation, since galactosyl removal alleviates steric hindrance for other enzymes in the xyloglucanolytic complex resulting in complete xyloglucan mobili-zation. Indeed, mixtures of TrBga1 with the alpha-xylosidase from Escherichia coli (YicI), which shows a preference towards non-galactosylated xyloglucan oligosaccharides, reveals efficient depolymerization when either enzyme is applied first. This understanding of the synergistic depolymerization contributes to the knowledge of plant cell wall structure, and reveals possible evolutionary mechanisms directing the preferences of debranching enzymes acting on xyloglucan oligosaccharides. (C) 2023 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM). All rights reserved.

Automated summary

Trichoderma reesei produces a beta-galactosidase that can hydrolyze xyloglucan oligosaccharides from tamarind and jatoba seed storage xyloglucans. The study found that the enzyme has a preference for galactosylated oligosaccharides and non-reducing end dexylosylated oligosaccharides. The synergistic depolymerization of xyloglucan by TrBga1 and alpha-xylosidase reveals insights into plant cell wall structure and evolutionary mechanisms of debranching enzymes.