Abstract：
Currently, fresh, unprocessed food has become a relevant element of the chain of transmission of enteropathogenic infections. To survive on a plant surface and further spread the infections, pathogens like Salmonella have to attach stably to the leaf surface. Adhesion, driven by various virulence factors, including the most abundant fim operon encoding type 1 fimbriae, is usually an initial step of infection, preventing physical removal of the pathogen. Adhesion properties of Salmonella\'s type 1 fimbriae and its FimH adhesin were investigated intensively in the past. However, there is a lack of knowledge regarding its role in interaction with plant cells. Understanding the mechanisms and structures involved in such interaction may facilitate efforts to decrease the risk of contamination and increase fresh food safety. Here, we applied Salmonella genome site-directed mutagenesis, adhesion assays, protein-protein interactions, and biophysics methods based on surface plasmon resonance to unravel the role of FimH adhesin in interaction with spinach leaves. We show that FimH is at least partially responsible for Salmonella binding to spinach leaves, and this interaction occurs in a mannose-independent manner. Importantly, we identified a potential FimH receptor as endo-1,3-β-d-Glucanase and found that this interaction is strong and specific, with a dissociation constant in the nanomolar range. This research advances our comprehension of Salmonella\'s interactions with plant surfaces, offering insights that can aid in minimizing contamination risks and improving the safety of fresh, unprocessed foods.
摘要：
目前,新鲜,未经加工的食品已成为肠致病性感染传播链的相关元素。为了在植物表面生存并进一步传播感染，沙门氏菌等病原体必须稳定地附着在叶片表面。附着力,由各种毒力因子驱动，包括编码1型菌毛的最丰富的fim操纵子，通常是感染的第一步，防止病原体的物理去除。过去对沙门氏菌1型菌毛及其FimH粘附素的粘附特性进行了深入研究。然而,缺乏关于其在与植物细胞相互作用中的作用的知识。了解这种相互作用所涉及的机制和结构可能有助于努力降低污染风险并提高新鲜食品的安全性。这里,我们应用沙门氏菌基因组定点诱变，粘附试验,蛋白质-蛋白质相互作用，和基于表面等离子体共振的生物物理学方法，以阐明FimH粘附素与菠菜叶相互作用的作用。我们表明，FimH至少部分负责沙门氏菌与菠菜叶的结合，并且这种相互作用以不依赖甘露糖的方式发生。重要的是,我们确定了一个潜在的FimH受体为内切-1,3-β-d-葡聚糖酶，并发现这种相互作用是强烈和特异性的，解离常数在纳摩尔范围内。这项研究促进了我们对沙门氏菌与植物表面相互作用的理解，提供见解，可以帮助最大限度地减少污染风险和提高新鲜食品的安全性，未加工食品。
