Yarava Jayasubba Reddy, Gautam Isha, Jacob Anand, Fu Riqiang, Wang Tuo
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.
National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.
J Am Chem Soc. 2025 May 21;147(20):17416-17432. doi: 10.1021/jacs.5c04054. Epub 2025 May 6.
Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling the rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: , , and , representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals 15 forms of -acetylglucosamine units in chitin, which coexists with chitosan, and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α-1,3-glucan with distinct structural origins and dynamics were identified in , important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating a soft matrix under antifungal stress. Eight α-1,2-mannan side chain variants in were resolved, highlighting the crucial role of mannan side chains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.
处于细胞环境中的碳水化合物聚合物呈现出高度多态的结构和动力学特性，这对其多样功能至关重要，但对其进行生化分析具有挑战性。质子检测固态核磁共振光谱具有高同位素丰度和灵敏度，能够对生物分子进行快速且高分辨率的结构表征。在此，一系列二维/三维氢检测固态核磁共振技术经过定制，用于研究三种常见致病真菌（分别代表丝状菌和酵母形态）的完全质子化或部分氘代细胞中的多糖。对乙酰化碳水化合物的选择性检测揭示了几丁质中15种形式的N - 乙酰葡糖胺单元，其与壳聚糖共存，并且仅在有限位点与蛋白质结合。这通过弛豫测量和无模型分析所得到的它们运动的不同序参数和有效相关时间得到了支持。在酿酒酵母中鉴定出5种具有不同结构起源和动力学的α - 1,3 - 葡聚糖形式，这对于这种缓冲多糖在抗真菌应激下发挥支持细胞壁力学和再生软基质的多种作用很重要。在白色念珠菌中解析出8种α - 1,2 - 甘露聚糖侧链变体，突出了甘露聚糖侧链在维持与其他细胞壁聚合物的相互作用以保持结构完整性方面的关键作用。这些方法为关键真菌多糖的功能结构提供了新见解，并为探索不同生物体中的碳水化合物生物合成和修饰创造了新机会。
