The complex glycans comprising ‘dietary fiber’ evade the limited repertoire of human digestive enzymes and hence feed the vast community of microbes in the lower gastrointestinal tract. As such, complex glycans drive the composition of the human gut microbiota and, in turn, influence diverse facets of our nutrition and health. To access these otherwise recalcitrant carbohydrates, gut bacteria produce coordinated, substrate-specific arsenals of carbohydrate-active enzymes, glycan-binding proteins, oligosaccharide transporters, and transcriptional regulators. A recent explosion of biochemical and enzymological studies of these systems has led to the discovery of manifold new carbohydrate-active enzyme (CAZyme) families. Crucially underpinned by structural biology, these studies have also provided unprecedented molecular insight into the exquisite specificity of glycan recognition in the diverse CAZymes and non-catalytic proteins from the HGM. The revelation of a multitude of new three-dimensional structures and substrate complexes constitutes a ‘gold rush’ in the structural biology of the human gut microbiota.

包含“膳食纤维”的复杂聚糖避开了人类消化酶的有限组成部分，因此为下消化道中的大量微生物群落提供了食物。因此，复杂的聚糖驱动人类肠道微生物群的组成，进而影响我们营养和健康的各个方面。为了获取这些原本顽固的碳水化合物，肠道细菌会产生协调的、底物特异性的碳水化合物活性酶、聚糖结合蛋白、寡糖转运蛋白和转录调节剂库。最近对这些系统的生化和酶学研究的爆炸式增长导致发现了多种新的碳水化合物活性酶 (CAZyme) 家族。在结构生物学的关键支持下，这些研究还提供了前所未有的分子洞察力，以了解 HGM 的各种 CAZymes 和非催化蛋白中聚糖识别的精细特异性。大量新的三维结构和底物复合物的揭示构成了人类肠道微生物群结构生物学的“淘金热”。