Lignin-polysaccharide interactions in plant secondary cell walls revealed by solid-state NMR
Lignin-polysaccharide interactions in plant secondary cell walls revealed by solid-state NMR
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DOI：
10.1038/s41467-018-08252-0
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发表时间：
2019-01-21
影响因子：
16.6
通讯作者：
Wang, Tuo
中科院分区：
文献类型：
--
作者：
Kang, Xue;Kirui, Alex;Wang, Tuo
木质素是一种复杂的芳香生物聚合物，可以增强和防水植物次生细胞壁，使树木的机械稳定性和木质部的长距离水分运输成为可能。木质素的去除是造纸和生物质转化为生物燃料的关键步骤，这促使人们努力重新设计木质素的生物合成。然而，木质素与壁多糖相互作用的物理性质尚不清楚。在这里，我们发现木质素自聚集形成高度疏水性和动态独特的纳米结构域，与木聚糖具有广泛的表面接触。在动态核极化的支持下，完整玉米茎的固态核磁共振光谱显示木质素与木聚糖的极性基序具有丰富的静电相互作用。木质素优先结合木聚糖为3倍或扭曲的2倍螺旋构象，表明木聚糖与纤维素的关系不密切。这些发现提高了我们对木质纤维素生物质分子水平组织的认识，为优化生物燃料和生物材料的收获后加工提供了结构基础。
Lignin is a complex aromatic biopolymer that strengthens and waterproofs plant secondary cell walls, enabling mechanical stability in trees and long-distance water transport in xylem. Lignin removal is a key step in paper production and biomass conversion to biofuels, motivating efforts to re-engineer lignin biosynthesis. However, the physical nature of lignin's interactions with wall polysaccharides is not well understood. Here we show that lignin self-aggregates to form highly hydrophobic and dynamically unique nanodomains, with extensive surface contacts to xylan. Solid-state NMR spectroscopy of intact maize stems, supported by dynamic nuclear polarization, reveals that lignin has abundant electrostatic interactions with the polar motifs of xylan. Lignin preferentially binds xylans with 3-fold or distorted 2-fold helical screw conformations, indicative of xylans not closely associated with cellulose. These findings advance our knowledge of the molecular-level organization of lignocellulosic biomass, providing the structural foundation for optimization of post-harvest processing for biofuels and biomaterials.