Brazilian Biorenewables National Laboratory (LNBR), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, 13083-970, Brazil.
NPJ Biofilms Microbiomes. 2024 Oct 14;10(1):105. doi: 10.1038/s41522-024-00578-6.
Gut microbiota members from the Bacteroidota phylum play a pivotal role in mammalian health and metabolism. They thrive in this diverse ecosystem due to their notable ability to cope with distinct recalcitrant dietary glycans via polysaccharide utilization loci (PULs). Our study reveals that a PUL from an herbivore gut bacterium belonging to the Bacteroidota phylum, with a gene composition similar to that in the human gut, exhibits extended functionality. While the human gut PUL targets mixed-linkage β-glucans specifically, the herbivore gut PUL also efficiently processes linear and substituted β-1,3-glucans. This gain of function emerges from molecular adaptations in recognition proteins and carbohydrate-active enzymes, including a β-glucosidase specialized for β(1,6)-glucosyl linkages, a typical substitution in β(1,3)-glucans. These findings broaden the existing model for non-cellulosic β-glucans utilization by gut bacteria, revealing an additional layer of functional and evolutionary complexity within the gut microbiota, beyond conventional gene insertions/deletions to intricate biochemical interactions.
厚壁菌门的肠道微生物成员在哺乳动物的健康和新陈代谢中起着关键作用。由于它们具有显著的能力，可以通过多糖利用基因座（PULs）应对不同的抗性膳食聚糖，因此它们在这个多样化的生态系统中得以茁壮成长。我们的研究表明，属于厚壁菌门的食草动物肠道细菌的 PUL 具有与人类肠道相似的基因组成，表现出扩展的功能。虽然人类肠道 PUL 专门针对混合链接 β-葡聚糖，但食草动物肠道 PUL 也能有效地处理线性和取代的β-1,3-葡聚糖。这种功能获得来自于识别蛋白和碳水化合物活性酶的分子适应，包括专门用于β(1,6)-葡萄糖苷键的β-葡萄糖苷酶，这是β(1,3)-葡聚糖中的一个典型取代基。这些发现拓宽了肠道细菌利用非纤维素β-葡聚糖的现有模型，揭示了肠道微生物群中除了传统的基因插入/缺失之外，还有一层更为复杂的功能和进化复杂性，涉及到复杂的生化相互作用。
