The recalcitrance of cellulosic biomass greatly hinders its enzymatic degradation. Expansins induce cell wall loosening and promote efficient cellulose utilization; however, the molecular mechanism underlying their action is not well understood. In this study, TlEXLX1, a fungal expansin from Talaromyces leycettanus JCM12802, was characterized in terms of phylogeny, synergy, structure, and mechanism of action. TlEXLX1 displayed varying degrees of synergism with commercial cellulase in the pretreatment of corn straw and filter paper. TlEXLX1 binds to cellulose via domain 2, mediated by CH–π interactions with residues Tyr291, Trp292, and Tyr327. Residues Asp237, Glu238, and Asp248 in domain 1 form hydrogen bonds with glucose units and break the inherent hydrogen bonding within the cellulose matrix. This study identified the expansin amino acid residues crucial for cellulose binding, and elucidated the structure and function of expansins in cell wall networks; this has potential applications in biomass utilization.

纤维素生物质的顽固性极大地阻碍了其酶促降解。膨胀蛋白诱导细胞壁松动并促进纤维素的有效利用；然而，它们作用的分子机制尚不清楚。在这项研究中，Tl EXLX1 是一种来自Talaromyces leycettanus JCM12802 的真菌扩张蛋白，在系统发育、协同作用、结构和作用机制方面进行了表征。Tl EXLX1 在玉米秸秆和滤纸的预处理中显示出与商业纤维素酶不同程度的协同作用。铊EXLX1 通过结构域 2 与纤维素结合，由 CH-π 与残基 Tyr291、Trp292 和 Tyr327 相互作用介导。结构域 1 中的残基 Asp237、Glu238 和 Asp248 与葡萄糖单元形成氢键，并破坏纤维素基质中固有的氢键。本研究确定了对纤维素结合至关重要的扩展蛋白氨基酸残基，并阐明了扩展蛋白在细胞壁网络中的结构和功能；这在生物质利用方面具有潜在应用。