Chitin is one of the most abundant natural biopolymers and serves as a critical structural component of extracellular matrices, including fungal cell walls and insect exoskeletons. As a linear polymer of β-(1,4)-linked N-acetylglucosamine, chitin is synthesized by chitin synthases, which are recognized as targets for antifungal and anti-insect drugs. In this study, we determine seven different cryo-electron microscopy structures of a Saccharomyces cerevisiae chitin synthase in the absence and presence of glycosyl donor, acceptor, product, or peptidyl nucleoside inhibitors. Combined with functional analyses, these structures show how the donor and acceptor substrates bind in the active site, how substrate hydrolysis drives self-priming, how a chitin-conducting transmembrane channel opens, and how peptidyl nucleoside inhibitors inhibit chitin synthase. Our work provides a structural basis for understanding the function and inhibition of chitin synthase.

甲壳素是最丰富的天然生物聚合物之一，是细胞外基质（包括真菌细胞壁和昆虫外骨骼）的关键结构成分。甲壳素是一种β-(1,4)-连接的N-乙酰氨基葡萄糖的线性聚合物，由甲壳素合酶合成，被认为是抗真菌和抗昆虫药物的靶标。在这项研究中，我们确定了在糖基供体、受体、产物或肽基核苷抑制剂不存在和存在的情况下酿酒酵母几丁质合酶的七种不同的冷冻电子显微镜结构。结合功能分析，这些结构显示了供体和受体底物如何在活性位点结合、底物水解如何驱动自启动、几丁质传导跨膜通道如何打开以及肽基核苷抑制剂如何抑制几丁质合酶。我们的工作为理解几丁质合酶的功能和抑制提供了结构基础。