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: 7616415
• 负责人: WILLIAM C FUQUA
• 金额: $ 26.68万
• 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/7616415
• 关键词: Adherence; Adhesions; Adhesives; Agrobacterium; Bacterial Adhesins; Bacterial Infections; Biochemical; Caulobacter; Caulobacter crescentus; Cell surface; Cells; Chemicals; Complement; DNA; DNA Microarray Chip; Disease; Disease Progression; Electron Microscopy; Environment; Flagella; Fluorescence Microscopy; Fostering; Gene Cluster; Gene Expression; Gene Transfer; Genes; Genetic; Genetic Screening; Genomics; Goals; Growth; Homologous Gene; Immunofluorescence Microscopy; Infection; Label; Lectin; Light; Mammalian Cell; Mediating; Microarray Analysis; Microbe; Microbial Biofilms; Microscopic; Microscopy; Molecular Genetics; Pathogenesis; Pathway interactions; Pattern; Phosphorous; Pilum; Plants; Play; Polysaccharides; Positioning Attribute; Process; Production; Property; Proteins; Reagent; Regulation; Regulon; Resolution; Rhizobium radiobacter; Role; Staining method; Stains; Structure; Surface; System; T-DNA; Techniques; Testing; Time; Tissues; Toxin; Type IV Secretion System Pathway; Virulence; antimicrobial; base; extracellular; fungus; insight; mutant; novel; pathogen; protein distribution; research study; response; 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）：最近发现了一种新型的含有外多糖的结构，该结构定位于tumefaciens细胞的单个极点，似乎可以促进与表面的细胞接触，从而假定作为粘连素起作用。在生长条件下刺激外多糖的产生或挤出，并受到限制性磷的刺激，并由Phor-Phob Two Component System调节。 A. tumefaciens是一种致病性微生物，可通过IV型分泌（T4S）系统将DNA和蛋白质直接传输到宿主细胞。几乎尚无关于在感染过程中曲霉附着在植物细胞上的机制。与哺乳动物病原体不同，对植物病原体中宿主细胞表面相互作用的了解有限。 A. tumefaciens（包括真菌和哺乳动物细胞）的广泛宿主范围以及其在各种表面上形成生物膜的倾向表明一种非常通用的粘附机制。有充分的文献证明，A。tumefaciens紧密连接到植物组织和非生物表面的极性方向。最近的证据表明，曲霉曲霉T4s也位于细胞的单极，类似于极性外多糖。这项研究将确定外多糖和T4S机器是否可以占据相同的电池，是否发生在表面定植期间，以及外多糖是否在生产感染中起作用。还将测试其他极性结构的共定位，即鞭毛和pili。将确定外多糖的化学成分，并分离其编码其合成，阐述和定位的基因。将检查外多糖的磷响应性调节的机制，并在适应对表面环境的调整期间将这种结构与其他粘附途径的整合。这项研究中产生的发现将阐明植物宿主相互作用期间的表面附着和生物膜形成的过程，包括实施T4S毒素递送系统。这种极性多糖的性质与花椰菜物种的粘合剂持有量相似，并表明这些结构可能比预期的更常见，并且可能提供新颖的抗菌靶标。致病性微生物农杆菌产生一种粘稠的含糖物质，集中在细胞的一端。我们正在使用分子遗传学，高分辨率显微镜和基因组分析研究这种结构在疾病和细菌存活中的作用。这项研究有望提供有关粘附与疾病进展之间关系的重要见解。