Syrjanen Johanna L, Nore Alexandre, Roselletti Elena, Chakraborty Tanmoy, Perera Rajika L, Wilson Duncan
W.M Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY 11724, USA.
Current Address: Institute of Biotechnology, HiLIFE, University of Helsinki, FI 00014, Helsinki, Finland.
bioRxiv. 2025 Jan 9:2025.01.09.632233. doi: 10.1101/2025.01.09.632233.
causes more than 400,000 life-threatening, and half a billion mucosal infections annually. In response to infection, the host limits availability of essential micronutrients, including zinc, to restrict growth of the invading pathogen. As assimilation of zinc is essential for pathogenicity, its limitation induces the secretion of the zincophore protein Pra1 to scavenge zinc from the host. Pra1 also plays a number of important roles in host-pathogen interactions and is conserved in most fungi. However, the structure of fungal zincophores is not known. Here, we present the first cryogenic electron microscopy structures of Pra1 in its apo- and zinc-bound states, at 2.8 and 2.5 Å resolution respectively. Our work reveals a hexameric ring-like assembly with multiple zinc binding sites. Through genetic studies, we show that one of these zinc binding sites is essential for growth under zinc restriction but does not affect the inflammatory properties of Pra1. These data provide a foundation for future work to explore the structural basis of Pra1-mediated host-pathogen interactions, zinc uptake, as well therapeutics development.
每年导致超过40万例危及生命的情况以及5亿例黏膜感染。作为对感染的反应，宿主会限制包括锌在内的必需微量营养素的可利用性，以限制入侵病原体的生长。由于锌的同化对于致病性至关重要，其限制会诱导锌载体蛋白Pra1的分泌，以从宿主中清除锌。Pra1在宿主-病原体相互作用中也发挥着许多重要作用，并且在大多数真菌中都保守存在。然而，真菌锌载体的结构尚不清楚。在此，我们分别以2.8 Å和2.5 Å的分辨率展示了Pra1处于无锌和结合锌状态下的首个低温电子显微镜结构。我们的研究揭示了一种具有多个锌结合位点的六聚体环状组装体。通过遗传学研究，我们表明这些锌结合位点之一对于锌限制条件下的生长至关重要，但不影响Pra1的炎症特性。这些数据为未来探索Pra1介导的宿主-病原体相互作用、锌摄取以及治疗药物开发的结构基础的工作提供了基础。
