Synthesis and function of a unipolar expolysaccharide in Agrobacterium

农杆菌单极胞外多糖的合成及功能

• 批准号: 7248928
• 负责人: WILLIAM C FUQUA
• 金额: $ 26.11万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7248928
• 关键词: Adherence; Adhesions; Adhesives; Agrobacterium; Bacterial Adhesins; Bacterial Infections; Biochemical; Biological; Caulobacter; Cell surface; Cells; Chemicals; Complement; Condition; DNA; Disease; Disease Progression; Electron Microscopy; Environment; Flagella; Fluorescence Microscopy; Fostering; Gene Transfer; Genes; Genetic; Genetic Screening; Genomics; Goals; Growth; Immunofluorescence Microscopy; Infection; Label; Lectin; Light; Localized; Mammalian Cell; Mediating; Microarray Analysis; Microbe; Microbial Biofilms; Microscopic; Microscopy; Molecular Genetics; Pathogenesis; Pathway interactions; Pattern; Personal Satisfaction; Phosphorous; Pilum; Plants; Play; Polysaccharides; Positioning Attribute; Process; Production; Property; Proteins; Range; Reagent; Regulation; Regulon; Research Personnel; Resolution; Rhizobium radiobacter; Role; Staining method; Stains; Structure; Surface; System; T-DNA; Techniques; Testing; Time; Tissues; Toxin; Type IV Secretion System Pathway; Virulence; antimicrobial; clay; comparative; extracellular; fungus; insight; mutant; novel; pathogen; programs; research study; sugar

DESCRIPTION (provided by applicant): A novel exopolysaccharide-containing structure has recently been discovered that localizes to a single pole of Agrobacterium tumefaciens cells and appears to promote cellular contact with surfaces, presumptively functioning as an adhesin. Production or extrusion of the exopolysaccharide is stimulated under growth conditions with limiting phosphorous and is regulated by the PhoR-PhoB two component system. A. tumefaciens is a pathogenic microbe that transfers DNA and proteins directly to plant host cells via a Type IV Secretion (T4S) system. There is virtually nothing known regarding the mechanism by which A. tumefaciens attaches to plant cells during the infection process. Unlike mammalian pathogens, there is limited understanding of host cell surface interactions in plant pathogens. The wide potential host range of A. tumefaciens, including fungi and mammalian cells, as well as its proclivity to form biofilms on diverse surfaces suggest an extremely versatile adhesion mechanism. It is well documented that A. tumefaciens tightly attaches to plant tissues and abiotic surfaces in a polar orientation. Recent evidence suggests that the A. tumefaciens T4S is also localized to a single pole of the cell, analogous to the polar exopolysaccharide. This study will determine whether the exopolysaccharide and the T4S machine can occupy the same pole of the cell, whether this occurs during surface colonization, and if the exopolysaccharide plays a role in productive infections. Co-localization of additional polar structures, flagella and pili, will also be tested. The chemical composition of the exopolysaccharide will be determined and the genes encoding its synthesis, elaboration and localization isolated. The mechanism of phosphorous-responsive regulation of the exopolysaccharide will be examined and the integration of this structure with other adhesion pathways during adaptation to the surface environment elucidated. The findings generated in this study will shed light on the process of surface attachment and biofilm formation during plant host interactions, including implementation of the T4S toxin delivery system. The properties of this polar polysaccharide are similar to the adhesive holdfast of Caulobacter species and suggest that these structures could be more common than anticipated, and may provide novel antimicrobial targets. The pathogenic microbe Agrobacterium tumefaciens produces a sticky, sugar-containing substance that concentrates on one end of cell. We are investigating the role of this structure in disease and bacterial survival using molecular genetics, high resolution microscopy and genomic analysis. This study promises to provide important insights into the relationship between adhesion and disease progression.

描述（由申请人提供）：最近发现了一种新颖的含有胞外多糖的结构，其定位于根癌农杆菌细胞的单极，并且似乎促进细胞与表面的接触，推测起到粘附素的作用。胞外多糖的产生或挤出在限制磷的生长条件下受到刺激，并受到 PhoR-PhoB 双组分系统的调节。 根癌农杆菌是一种病原微生物，可通过 IV 型分泌 (T4S) 系统将 DNA 和蛋白质直接转移至植物宿主细胞。关于根癌农杆菌在感染过程中附着在植物细胞上的机制几乎一无所知。与哺乳动物病原体不同，对植物病原体宿主细胞表面相互作用的了解有限。根癌农杆菌的潜在宿主范围广泛，包括真菌和哺乳动物细胞，以及它在不同表面上形成生物膜的倾向，表明其具有极其通用的粘附机制。据充分证明，根癌农杆菌以极性方向紧密附着在植物组织和非生物表面上。最近的证据表明，根癌农杆菌 T4S 也定位于细胞的单极，类似于极性胞外多糖。这项研究将确定胞外多糖和T4S机器是否可以占据细胞的同一极，这是否发生在表面定植期间，以及胞外多糖是否在生产性感染中发挥作用。还将测试其他极性结构、鞭毛和菌毛的共定位。将确定胞外多糖的化学组成，并分离编码其合成、加工和定位的基因。将检查胞外多糖的磷响应调节机制，并阐明在适应表面环境过程中该结构与其他粘附途径的整合。本研究的结果将揭示植物宿主相互作用期间表面附着和生物膜形成的过程，包括 T4S 毒素输送系统的实施。这种极性多糖的特性与柄杆菌属的粘着力相似，表明这些结构可能比预期更常见，并且可能提供新的抗菌靶点。病原微生物根癌农杆菌产生一种粘性含糖物质，集中在细胞的一端。我们正在利用分子遗传学、高分辨率显微镜和基因组分析来研究这种结构在疾病和细菌存活中的作用。这项研究有望为粘附与疾病进展之间的关系提供重要的见解。