Vandborg Bethiney C, Horsfall Aimee J, Pederick Jordan L, Abell Andrew D, Bruning John B
Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide 5005, Australia.
School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia.
J Fungi (Basel). 2023 Nov 10;9(11):1098. doi: 10.3390/jof9111098.
Invasive fungal infections (IFIs) are prevalent in immunocompromised patients. Due to alarming levels of increasing resistance in clinical settings, new drugs targeting the major fungal pathogen are required. Attractive drug targets are those involved in essential processes like DNA replication, such as proliferating cell nuclear antigens (PCNAs). PCNA has been previously studied in cancer research and presents a viable target for antifungals. Human PCNA interacts with the p21 protein, outcompeting binding proteins to halt DNA replication. The affinity of p21 for hPCNA has been shown to outcompete other associating proteins, presenting an attractive scaffold for peptidomimetic design. p21 has no homolog to our knowledge, yet our group has previously demonstrated that human p21 can interact with PCNA (afumPCNA). This suggests that a p21-based inhibitor could be designed to outcompete the native binding partners of afumPCNA to inhibit fungal growth. Here, we present an investigation of extensive structure-activity relationships between designed p21-based peptides and afumPCNA and the first crystal structure of a p21 peptide bound to afumPCNA, demonstrating that the replication model uses a PIP-box sequence as the method for binding to afumPCNA. These results inform the new optimized secondary structure design of a potential peptidomimetic inhibitor of afumPCNA.
侵袭性真菌感染（IFI）在免疫功能低下的患者中很普遍。由于临床环境中耐药性的增加令人担忧，因此需要针对主要真菌病原体的新药。有吸引力的药物靶点是那些参与DNA复制等基本过程的靶点，例如增殖细胞核抗原（PCNA）。PCNA此前已在癌症研究中得到研究，是抗真菌药物的一个可行靶点。人类PCNA与p21蛋白相互作用，取代结合蛋白以阻止DNA复制。p21对hPCNA的亲和力已被证明能取代其他相关蛋白，为拟肽设计提供了一个有吸引力的支架。据我们所知，p21没有同源物，但我们的团队此前已证明人类p21可以与烟曲霉PCNA（afumPCNA）相互作用。这表明可以设计一种基于p21的抑制剂来取代afumPCNA的天然结合伙伴，从而抑制真菌生长。在此，我们展示了对基于p21的设计肽与afumPCNA之间广泛的构效关系的研究，以及与afumPCNA结合的p21肽的首个晶体结构，证明复制模型使用PIP盒序列作为与afumPCNA结合的方法。这些结果为afumPCNA潜在拟肽抑制剂的新优化二级结构设计提供了依据。
