Role of glycans in bacteria-host interactions

多糖在细菌-宿主相互作用中的作用细菌通过高度特异性和非特异性的相互作用附着在哺乳动物细胞上。粘蛋白糖蛋白衬里的粘膜是抵御入侵微生物的第一道防线。此外，细菌可以形成生物膜，对免疫系统构成防御。在世界范围内至关重要的是已经产生抗生素抗药性的细菌，如鲍曼不动杆菌。细菌胞外多糖在与宿主高度复杂的动态相互作用中发挥重要作用，保护细菌免受宿主免疫系统、恶劣环境和抗生素的侵害，是重要的毒力因子，对生物膜的形成至关重要。鲍曼不动杆菌黏附于宿主和生物膜内的分子细节和机制大多尚不清楚。细菌中导致复杂多糖的生物合成酶和机制也仍然难以捉摸。我们过去的研究主要集中在哺乳动物糖蛋白的生物合成上，这些糖蛋白是细菌的受体，在炎症和许多疾病中都受到调节。随后，我们发现了O抗原合成的生物合成途径，重点是病原菌。我们现在将结合这两个专业领域来定义细菌和宿主粘液之间相互作用的机制和结构细节。因此，我们将通过a)定义细菌多糖合成的酶和机制，b)研究特定细菌酶在生物膜形成和粘液黏附中的作用和抑制来解决细菌与宿主的相互作用。C)确定粘液结构在细菌相互作用中的作用，d)开发减少细菌-宿主相互作用的方法。这些研究的结果将填补我们对鲍曼不动杆菌毒力因子知识的空白，并将导致开发减少与宿主粘膜的黏附、阻止生物膜形成和减少细菌感染的方法。该项目包括重新设计粘蛋白多糖，以探索它们在细菌黏附中的作用。我们将与糖生物学的合作者和专业人员一起提供底物，并探索细菌蛋白质糖基化的途径和机制。抑制剂的设计和编码该途径中特定酶的基因的缺失将揭示它们在多糖组装、生物膜形成和宿主相互作用中的作用。在拟议的工作中，学生将有机会发现多糖组装的新机制，研究细菌生物膜的形成和对人体细胞的黏附，分析对细菌相互作用至关重要的糖链结构，生物信息学，转基因方法，糖链和蛋白质结构，并开发药物靶标。在这项工作中获得的知识可以转化为新的抗菌策略，鉴于威胁生命的抗生素耐药性，这些策略是迫切需要的。

Title: Role of glycans in bacteria-host interactions Bacteria adhere to mammalian cells through both highly specific and non-specific interactions. Mucous membranes lined with mucin glycoproteins are a first line of defense against invading microbes. In addition, bacteria can form biofilms that present a defense against the immune system. Of critical world wide importance are bacteria that have developed antibiotic resistance such as Acinetobacter baumannii. The extracellular polysaccharides of bacteria play important roles in the highly complex and dynamic interactions with the host, protecting bacteria from the host immune system, harsh environment and antibiotics, and are important virulence factors and are critical for the formation of biofilms. The molecular details and mechanisms of A. baumannii adhesion to the host and within biofilms are mostly unknown. The biosynthetic enzymes and mechanisms leading to complex glycans in bacteria also remain elusive. Our past research has focused on the biosynthesis of mammalian glycoproteins that are receptors for bacteria and are regulated during inflammation and in many diseases. Subsequently we discovered biosynthetic pathways in the synthesis of O antigens with a focus on pathogenic bacteria. We will now combine these two areas of expertise in defining the mechanisms and structural details of the interactions between bacteria and host mucus. We will thus address bacteria-host interactions by a) defining the enzymes and mechanisms of bacterial polysaccharide synthesis, b) studying the role and inhibition of specific bacterial enzymes in biofilm formation and mucus adhesion. c) determining the roles of mucus structures in bacterial interactions, d) developing methods to reduce bacteria-host interactions. The results from these studies will fill a gap in our knowledge of A. baumannii virulence factors and will lead to development of methodologies to reduce adhesion to host mucosa, to block biofilm formation and reduce bacterial infection. The project includes the reengineering of mucin glycans in order to explore their role in bacterial adhesion. With a team of collaborators and expertise in glycobiology we will provide substrates and explore bacterial protein glycosylation pathways and mechanisms. The design of inhibitors and deletion of genes encoding specific enzymes in the pathway will reveal their role in polysaccharide assembly, in biofilm formation and host interactions. In the proposed work, students will have the opportunity to discover new mechanisms of polysaccharide assembly, to study bacterial biofilm formation and adherence to human cells, analyze glycan structures critical for bacterial interactions, bioinformatics, transfection methods, glycan and protein structures and develop drug targets. The knowledge gained in this work can be translated into new anti¬bacterial strategies that are urgently needed in light of life threatening antibiotic resistance.