ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, Australia.
ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, Australia
mBio. 2021 Apr 13;12(2):e03540-20. doi: 10.1128/mBio.03540-20.
The fungi are an enormously successful eukaryotic lineage that has colonized every aerobic habitat on Earth. This spectacular expansion is reflected in the dynamism and diversity of the fungal cell wall, a matrix of polysaccharides and glycoproteins pivotal to fungal life history strategies and a major target in the development of antifungal compounds. Cell wall polysaccharides are typically synthesized by Leloir glycosyltransferases, enzymes that are notoriously difficult to characterize, but their nucleotide-sugar substrates are well known and provide the opportunity to inspect the monosaccharides available for incorporation into cell wall polysaccharides and glycoproteins. In this work, we have used phylogenomic analyses of the enzymatic pathways that synthesize and interconvert nucleotide-sugars to predict potential cell wall monosaccharide composition across 491 fungal taxa. The results show a complex evolutionary history of these cell wall enzyme pathways and, by association, of the fungal cell wall. In particular, we see a significant reduction in monosaccharide diversity during fungal evolution, most notably in the colonization of terrestrial habitats. However, monosaccharide distribution is also shown to be varied across later-diverging fungal lineages. This study provides new insights into the complex evolutionary history of the fungal cell wall. We analyzed fungal enzymes that convert sugars acquired from the environment into the diverse sugars that make up the fundamental building blocks of the cell wall. Species-specific profiles of these nucleotide-sugar interconverting (NSI) enzymes for 491 fungi demonstrated multiple losses and gains of NSI proteins, revealing the rich diversity of cell wall architecture across the kingdom. Pragmatically, because cell walls are essential to fungi, our observations of variation in sugar diversity have important implications for the development of antifungal compounds that target the sugar profiles of specific pathogens.
真菌是一个极其成功的真核生物谱系，已经占领了地球上所有有氧的栖息地。这种惊人的扩张反映在真菌细胞壁的活力和多样性上，细胞壁是多糖和糖蛋白的基质，对真菌的生活史策略至关重要，也是开发抗真菌化合物的主要目标。细胞壁多糖通常由 Leloir 糖基转移酶合成，这些酶的特性很难被描述，但它们的核苷酸糖底物是众所周知的，这为研究可用于细胞壁多糖和糖蛋白合成的单糖提供了机会。在这项工作中，我们利用合成和相互转化核苷酸糖的酶途径的系统基因组分析，预测了 491 种真菌类群中潜在的细胞壁单糖组成。结果表明，这些细胞壁酶途径的进化历史复杂，与之相关的还有真菌细胞壁的进化历史。特别是，我们看到真菌进化过程中单糖多样性显著减少，特别是在陆地栖息地的定殖过程中。然而，单糖的分布在后来分化的真菌谱系中也表现出多样化。这项研究为真菌细胞壁的复杂进化历史提供了新的见解。我们分析了将环境中获取的糖转化为构成细胞壁基本结构单元的不同糖的真菌酶。对 491 种真菌的这些核苷酸糖转化 (NSI) 酶的种特异性分析表明，NSI 蛋白存在多种缺失和获得，揭示了王国内细胞壁结构的丰富多样性。从实际应用的角度来看，由于细胞壁对真菌至关重要，我们对糖多样性变化的观察对开发针对特定病原体糖谱的抗真菌化合物具有重要意义。
