Biosynthesis and regulation of a unipolar polysaccharide in Agrobacterium

农杆菌中单极性多糖的生物合成和调控

• 批准号: 9384094
• 负责人: WILLIAM C FUQUA
• 金额: $ 36.44万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-08 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9384094
• 关键词: Acids; Adhesions; Adhesives; Affect; Agriculture; Agrobacterium; Alphaproteobacteria; Anabolism; Anti-Bacterial Agents; Automobile Driving; Bacteria; Bacterial Adhesins; Bacterial Infections; Bacterial Model; Biochemical; Biocompatible Materials; Biogenesis; Biological; Biomedical Engineering; Biosynthetic Proteins; Caulobacter; Caulobacter crescentus; Cell physiology; Cell surface; Cells; Chemicals; Chronic; Collection; Communities; Complex; Dependence; Development; Disease; Environment; Environmental Risk Factor; Evaluation; Genes; Genetic; Genetic Screening; Genomics; Growth; Individual; Industrialization; Infection; Lead; Lectin; Mediating; Medical; Medical Device; Microbial Biofilms; Modeling; Monosaccharides; Pathway interactions; Pattern; Periodicity; Phenotype; Physiological; Polysaccharides; Process; Production; Property; Proteins; Pterins; Regulation; Rhizobium radiobacter; Role; Second Messenger Systems; Signal Pathway; Signal Transduction; Specificity; Structure; Surface; Swimming; System; Technology; Variant; antimicrobial; base; cell motility; cellular development; experimental study; imaging approach; improved; insight; medical implant; member; microscopic imaging; mutant; novel; pathogen; periplasm; phosphoric diester hydrolase; prevent; response; retinal rods; spatial relationship

PROJECT SUMMARY The establishment of productive, stable surface interactions is an important process for bacteria, that can lead to formation of the adherent communities known as biofilms. These assemblages are challenges in agricultural, industrial and medical settings, and are intrinsically tolerant to many antimicrobial therapies. For a number of bacteria in the large and diverse Alphaproteobacteria (APB) group, attachment to surfaces and to other cells requires production of a structure comprised of polysaccharide localized to a single cellular pole. In the model pathogen Agrobacterium tumefaciens this structure is called the unipolar polysaccharide (UPP). Polar adhesins similar to the UPP are widespread among the APB, including other pathogens and symbionts, and the A. tumefaciens UPP is therefore a representative model for these diverse bacteria. Among these, the stalked bacterium Caulobacter crescentus produces a similar structure called the holdfast at the stalk tip, and although it has been well studied, remains poorly understood and is less broadly representative than the UPP. These polar polysaccharides can drive stable surface attachment and host interactions. In A. tumefaciens the UPP is comprised of at least two distinct polysaccharide species, and the genes required for synthesis suggest that there may be overlapping biosynthesis pathways. We aim to determine how A. tumefaciens coordinates and regulates production of these polysaccharides during surface colonization, including dynamic localization of the biosynthetic complexes. Production of the A. tumefaciens UPP is strictly regulated by contact with the surface, and cells rarely if ever produce the UPP when free-swimming. The proposed studies will dramatically improve our current understanding of UPP properties and biosynthesis, and will elucidate its regulation via a network of intracellular signal cascades, its surface-dependent polar localization, and other environmental signals that affect its production, and thereby attachment. At the core of this control network is the ubiquitous bacterial second messenger cyclic diguanylate monophosphate, which regulates UPP production. Among the primary UPP regulatory mechanisms are a novel signaling pathway involving small metabolites called pterins, and the response to low pH. The project utilizes an extensive collection of genetic mutants and variants, quantitative microscopic imaging approaches, genomic technology, and sophisticated biochemical approaches to illuminate the cellular processes that promote attachment via the UPP. The findings generated will contribute to the understanding of the motile to sessile transition and initiation of biofilm formation. We will characterize the biosynthesis of a novel biological adhesive(s) and a potential antimicrobial target, and will reveal how bacterial cells control production of these important products to promote surface interactions that lead to biofilm formation. Our findings will provide fundamental information about these polar adhesins, identifying new targets for anti-bacterial approaches and facilitating development of new biomaterials.

项目概要 建立高效、稳定的表面相互作用对于细菌来说是一个重要的过程， 可以导致称为生物膜的粘附群落的形成。这些组合是挑战 农业、工业和医疗环境，并且对许多抗菌疗法具有内在耐受性。对于一个 大型且多样化的 Alphaproteobacteria (APB) 群中的细菌数量、对表面和表面的附着 其他细胞需要产生由定位于单个细胞极的多糖组成的结构。在 模型病原体根癌农杆菌的这种结构称为单极多糖（UPP）。 类似于 UPP 的极性粘附素在 APB 中广泛存在，包括其他病原体和共生体， 因此，根癌农杆菌 UPP 是这些不同细菌的代表性模型。其中， 有茎细菌新月柄杆菌在茎尖产生一种类似的结构，称为固定器，并且 尽管它已经得到了充分的研究，但人们对它的了解仍然很少，并且不如 UPP 具有广泛的代表性。 这些极性多糖可以驱动稳定的表面附着和宿主相互作用。在根瘤农杆菌中 UPP 由至少两种不同的多糖种类组成，合成所需的基因表明 可能存在重叠的生物合成途径。我们的目标是确定农杆菌如何协调 并在表面定植过程中调节这些多糖的产生，包括动态定位 的生物合成复合物。根癌农杆菌 UPP 的生产受到与 表面，细胞在自由游动时很少产生 UPP。拟议的研究将显着 提高我们目前对 UPP 特性和生物合成的理解，并将通过 细胞内信号级联网络、其表面依赖性极性定位以及其他环境 影响其产生的信号，从而影响其附着。该控制网络的核心是无处不在的 细菌第二信使环二鸟苷单磷酸盐，调节 UPP 的产生。其中 主要的 UPP 调节机制是一种新颖的信号传导途径，涉及称为蝶呤的小代谢物， 以及对低pH值的反应。该项目利用了大量的基因突变体和变体， 定量显微成像方法、基因组技术和复杂的生化方法 阐明通过 UPP 促进附着的细胞过程。所产生的发现将有助于 了解从运动到固着的转变和生物膜形成的启动。我们将表征 新型生物粘合剂和潜在抗菌靶点的生物合成，并将揭示如何 细菌细胞控制这些重要产物的产生，以促进导致生物膜的表面相互作用 形成。我们的研究结果将提供有关这些极性粘附素的基本信息，识别新的 抗菌方法的目标和促进新生物材料的开发。