The fundamental and assorted roles of β-1,3-glucans in nature are underpinned on diverse chemistry and molecular structures, demanding sophisticated and intricate enzymatic systems for their processing. In this work, the selectivity and modes of action of a glycoside hydrolase family active on β-1,3-glucans were systematically investigated combining sequence similarity network, phylogeny, X-ray crystallography, enzyme kinetics, mutagenesis and molecular dynamics. This family exhibits a minimalist and versatile (α/β)-barrel scaffold, which can harbor distinguishing exo or endo modes of action, including an ancillary-binding site for the anchoring of triple-helical β-1,3-glucans. The substrate binding occurs via a hydrophobic knuckle complementary to the canonical curved conformation of β-1,3-glucans or through a substrate conformational change imposed by the active-site topology of some fungal enzymes. Together, these findings expand our understanding of the enzymatic arsenal of bacteria and fungi for the breakdown and modification of β-1,3-glucans, which can be exploited for biotechnological applications.

β-1,3-葡聚糖在自然界中的基本和各种作用以不同的化学和分子结构为基础，需要复杂的酶系统进行加工。在这项工作中，结合序列相似性网络、系统发育、X 射线晶体学、酶动力学、诱变和分子动力学，系统地研究了对 β-1,3-葡聚糖有活性的糖苷水解酶家族的选择性和作用模式。该家族展示了一种极简且多功能的 (α/β)-桶支架，它可以具有不同的外切或内切作用模式，包括用于锚定三螺旋 β-1,3-葡聚糖的辅助结合位点。底物结合通过与 β-1 的典型弯曲构象互补的疏水关节发生，3-葡聚糖或通过某些真菌酶的活性位点拓扑结构强加的底物构象变化。总之，这些发现扩大了我们对细菌和真菌用于分解和修饰 β-1,3-葡聚糖的酶库的理解，可用于生物技术应用。