Novel Mechanisms of Peptidoglycan Synthesis in Tannerella forsythia

连翘坦纳菌肽聚糖合成的新机制

• 批准号: 8700049
• 负责人: Ashu Sharma
• 金额: $ 23.85万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-05 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8700049
• 关键词: Acetylglucosamine; Amino Sugars; Animal Model; Bacteria; Biochemical Pathway; Cell Wall; Cell surface; Cells; Characteristics; Chronic; Complex; Computer Simulation; Data; Disease; Endodontics; Enzymes; Escherichia coli; Forsythia; Funding; Gene Cluster; Gene Expression Profile; Gene Expression Profiling; Genes; Genome; Genomic Library; Gingiva; Glycoproteins; Gram-Negative Bacteria; Growth; Homologous Gene; Human; In Vitro; Infection; Inflammation; Inflammatory; Isomerase; Knowledge; Label; Lactamase; Lead; Location; Membrane; Metabolic; Metabolic Pathway; Metabolism; Microbial Biofilms; Muramic Acid; N-acetylmuramic acid; Neuraminidase; Nutritional Requirements; Operon; Oral cavity; Orthologous Gene; Pathogenesis; Pathway interactions; Peptidoglycan; Periodontal Diseases; Periodontitis; Phosphotransferases; Physiological; Physiology; Porphyromonas gingivalis; Production; Proteins; Radiolabeled; Recycling; Reporter; Reproduction; Role; Sialic Acids; Sialoglycoproteins; System; Testing; Tissues; Tooth Diseases; Tooth Loss; Treponema denticola; anhydro-N-acetylmuramic acid; antimicrobial; antimicrobial drug; base; bone; design; in vivo; inhibitor/antagonist; insight; mimetics; mutant; novel; oral bacteria; pathogen; permease; public health relevance; radiotracer; salivary mucins; sialic acid permease; small molecule; sugar; transcriptome sequencing; uptake

DESCRIPTION (provided by applicant): Periodontitis is a chronic inflammatory disease of the tooth supporting tissue that leads to tooth loss. The disease results from the inflammation triggered by a group of Gram-negative pathogens that colonize the gingival and sub-gingival locations as polymicrobial biofilms. One of the pathogens present in these biofilms and strongly implicated in periodontitis is Tannerella forsythia. Its role in pathogenesis has been confirmed by reproduction of the disease (periodontal bone destruction) in animal models following infection with the bacterium. Uniquely, T. forsythia requires exogenous MurNAc, an essential peptidoglycan aminosugar, for growth. To date, this has not been observed for other pathogens but is likely due to the absence of genes encoding the key enzyme in its genome for the de novo synthesis of MurNAc from simple sugars. Moreover, despite its clear ability to utilize exogenously supplied MurNAc, the Tannerella genome also lacks homologs of PTS-type MurNAc transporters present in other bacteria. These unique characteristics suggest that novel mechanisms for MurNAc uptake and utilization exist in the bacterium. Surprisingly, T. forsythia can grow in in vitro biofilms in the absence of MurNAc if sialic acid-containing sialoglycoproteins are supplemented instead. We predict that in vivo the MurNAc requirements of the bacterium are fulfilled by scavenging muropeptides and MurNAc released by cohabiting bacteria during their cell wall recycling and during biofilm growth by MurNAc synthesis from sialic acid, which is most likely made available in vivo by the action of bacterial sialidase(s) on host glycoproteins. Thus, the objectives of this study are to define the mechanisms by which T. forsythia transports exogenous MurNAc for peptidoglycan synthesis (Aim1), and discover the metabolic pathways by which MurNAc is synthesized from sialic acid in the bacterium (Aim 2). Overall, this study will provide a basic understanding of the unique physiology of T. forsythia in relation to MurNAc uptake/utilization as well as novel insights into the nutritional requirements of the bacterium in the human oral cavity. This knowledge will aid in designing new antimicrobial agents targeting MurNAc uptake/utilization pathways to control T. forsythia growth. Moreover, the information will be valuable for understanding other bacteria which have not yet been cultivated/identified but might have similar physiological requirements.

描述（由申请人提供）：牙周炎是牙齿支持组织的一种慢性炎症性疾病，会导致牙齿脱落。该疾病是由一组革兰氏阴性病原体引发的炎症引起的，这些病原体以多种微生物生物膜的形式定殖在牙龈和龈下位置。存在于这些生物膜中并与牙周炎密切相关的病原体之一是连翘坦纳氏菌。其在发病机制中的作用已被证实 感染细菌后在动物模型中繁殖疾病（牙周骨破坏）。独特的是，连翘需要外源 MurNAc（一种必需的肽聚糖氨基糖）才能生长。迄今为止，尚未在其他病原体中观察到这种情况，但这可能是由于其基因组中缺乏编码从单糖从头合成 MurNAc 的关键酶的基因。此外，尽管其明显能够利用外源提供的 MurNAc，但 Tannerella 基因组也缺乏其他细菌中存在的 PTS 型 MurNAc 转运蛋白的同源物。这些独特的特征表明细菌中存在摄取和利用 MurNAc 的新机制。令人惊讶的是，如果含有唾液酸的唾液酸糖蛋白，连翘可以在没有 MurNAc 的情况下在体外生物膜中生长 而是进行补充。我们预测，在体内，细菌对 MurNAc 的需求是通过清除共居细菌在细胞壁回收过程中释放的 MurNAc 和 MurNAc 来满足的，并且在生物膜生长过程中，通过唾液酸合成 MurNAc，这很可能是通过细菌唾液酸酶对宿主糖蛋白的作用在体内获得的。因此，本研究的目的是明确连翘转运外源 MurNAc 进行肽聚糖合成的机制（目标 1），并发现细菌中唾液酸合成 MurNAc 的代谢途径（目标 2）。总的来说，这项研究将提供对连翘与 MurNAc 吸收/利用相关的独特生理学的基本了解，以及对人类口腔中细菌的营养需求的新见解。这些知识将有助于设计针对 MurNAc 吸收/利用途径的新抗菌剂，以控制连翘生长。此外，这些信息对于了解尚未培养/鉴定但可能具有类似生理需求的其他细菌也很有价值。