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(申请人提供)：牙周炎是一种牙齿支持组织的慢性炎症性疾病，导致牙齿脱落。这种疾病是由一组革兰氏阴性病原体引发的炎症引起的，这些病原体以多菌生物膜的形式定植在牙龈和龈下位置。其中一种存在于这些生物膜中并与牙周炎密切相关的病原体是连翘坦纳氏菌。它在发病机制中的作用已被证实 在感染细菌后的动物模型中复制疾病(牙周骨破坏)。独一无二的是，连翘生长需要外源MurNAc，这是一种必不可少的肽聚糖氨基糖。到目前为止，还没有在其他病原体中观察到这种情况，但可能是因为在其基因组中缺乏编码从单糖合成MurNAc的关键酶的基因。此外，尽管坦纳氏菌明显有能力利用外源供应的MurNAc，但它的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，在没有MurNAc的情况下，连翘可以在体外生物膜中生长，如果含唾液酸的唾液酸糖蛋白 而不是补充。我们预测，在体内，细菌对MurNAc的需求是通过清除共生细菌在细胞壁循环过程中以及在生物膜生长过程中通过唾液酸合成MurNAc释放的神经肽和MurNAc来实现的，这很可能是通过细菌唾液酸酶(S)对宿主糖蛋白的作用在体内实现的。因此，本研究的目的是确定连翘运输外源MurNAc用于肽聚糖合成(Aim1)的机制，并发现在细菌中从唾液酸合成MurNAc的代谢途径(Aim2)。总体而言，这项研究将提供对连翘与MurNAc吸收/利用有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新的抗菌剂，针对MurNAc的吸收/利用途径来控制连翘的生长。此外，这些信息将对了解其他尚未培养/鉴定但可能具有类似生理需求的细菌具有价值。