Fernando Liyanage D, Dickwella Widanage Malitha C, Shekar S Chandra, Mentink-Vigier Frederic, Wang Ping, Wi Sungsool, Wang Tuo
Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.
National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA.
J Struct Biol X. 2022 Jul 19;6:100070. doi: 10.1016/j.yjsbx.2022.100070. eCollection 2022.
Fungal infections cause high mortality in immunocompromised individuals, which has emerged as a significant threat to human health. The efforts devoted to the development of antifungal agents targeting the cell wall polysaccharides have been hindered by our incomplete picture of the assembly and remodeling of fungal cell walls. High-resolution solid-state nuclear magnetic resonance (ss NMR) studies have substantially revised our understanding of the polymorphic structure of polysaccharides and the nanoscale organization of cell walls in and multiple other fungi. However, this approach requires C/N-enrichment of the sample being studied, severely restricting its application. Here we employ the dynamic nuclear polarization (DNP) technique to compare the unlabeled cell wall materials of and prepared using both liquid and solid media. For each fungus, we have identified a highly conserved carbohydrate core for the cell walls of conidia and mycelia, and from liquid and solid cultures. Using samples prepared in different media, the recently identified function of α-glucan, which packs with chitin to form the mechanical centers, has been confirmed through conventional ss NMR measurements of polymer dynamics. These timely efforts not only validate the structural principles recently discovered for cell walls in different morphological stages, but also open up the possibility of extending the current investigation to other fungal materials and cellular systems that are challenging to label.
真菌感染在免疫功能低下的个体中会导致高死亡率，这已成为对人类健康的重大威胁。针对真菌细胞壁多糖开发抗真菌药物的努力因我们对真菌细胞壁组装和重塑的认识不完整而受到阻碍。高分辨率固态核磁共振（ss NMR）研究极大地改变了我们对多糖多晶型结构以及酿酒酵母和多种其他真菌细胞壁纳米级组织的理解。然而，这种方法需要对所研究的样品进行碳/氮富集，严重限制了其应用。在这里，我们采用动态核极化（DNP）技术来比较使用液体和固体培养基制备的酿酒酵母和白色念珠菌的未标记细胞壁材料。对于每种真菌，我们都确定了分生孢子和菌丝体细胞壁以及液体和固体培养物中的高度保守的碳水化合物核心。使用在不同培养基中制备的样品，通过对聚合物动力学的传统ss NMR测量，证实了最近发现的α-葡聚糖与几丁质堆积形成机械中心的功能。这些及时的努力不仅验证了最近发现的不同形态阶段酿酒酵母细胞壁的结构原理，还开辟了将当前研究扩展到其他难以标记的真菌材料和细胞系统的可能性。
