Cell surface biogenesis in Streptococcus pneumoniae

项目总结 致病菌的细胞表面含有许多关键的毒力因子，这些因子被用来与 主持人。细胞表面聚合物还包含先天免疫系统识别的分子签名，以 激活防御反应，表面分子或其生物发生途径是重要的靶标 用于我们许多最有效的疫苗和抗生素疗法。对机制有更好的理解 因此，负责细菌表面组装几乎将影响致病机理研究的所有领域 通知新的感染治疗方法的发展。尽管细胞表面组装的某些方面可以 从对非致病生物的研究中推断，这些模型的结果永远不会完全预测。 与模型的偏离对于链球菌等病原体来说可能尤其明显。 肺炎杆菌(Sp)采用不同的(卵圆形)形态，并通过与杆状不同的机制生长 像大肠杆菌和枯草芽孢杆菌这样的生物，它们的细胞表面组装研究传统上 被调查过了。SP是幼儿和老年人中威胁生命的疾病的主要原因， 这种细菌耐药感染的发生率正在上升。多价Sp的药效 疫苗的数量也在下降，因为出现了表面多糖发生变化而逃逸的菌株 疫苗诱导的免疫力。因此，重要的是找出阻止SP增长的新方法。为了做到这一点，我们 已经启动了一个项目来研究Sp的细胞表面组装，该项目利用了 鲁德纳和伯恩哈特在细胞壁生物发生、革兰氏阳性生物学、显微镜、生物化学、 和遗传学。重要的是，我们的方法并不局限于对经过充分研究的细胞的同系物进行表征。 杆状模式生物的形态发生因子。相反，我们正在利用前进的优势 由现代测序方法提供动力的基因筛查，以发现新的参与者和生物机制 参与Sp增长。我们的初步遗传分析发现了青霉素的两种新的调节剂- Sp.的结合蛋白(PBPs)。这些是在革兰氏阳性细菌中发现的第一组控制 这些关键的细胞壁合成酶的活性。该项目的第一个目标将通过以下方式来研究这种机制 这些因子调节PBP的活性，并将这些酶的功能与其他成分联系起来 形态发生系统的。除了控制PBP的活性外，适当的表面组装还需要 对裂解细胞壁的酶的调节。控制这些酶活性的因素很少。 在所有细菌中都能理解。我们的第二个目标将建立在有希望的结果上，我们已经确定了一个监管机构 被称为脂磷壁酸(LTA)的表面聚合物在控制细胞壁水解酶活性中的作用 LytA负责β-内酰胺治疗后Sp细胞的裂解。总体而言，我们的结果有望发现新的 阻止细胞壁组装或触发自溶以用于治疗开发的方法。

PROJECT SUMMARY The cell surface of pathogenic bacteria contains many key virulence factors that are used to interface with the host. Cell surface polymers also contain the molecular signatures recognized by the innate immune system to activate a defensive response, and surface molecules or their biogenesis pathways serve as important targets for many of our most effective vaccine and antibiotic therapies. A better understanding of the mechanisms responsible for bacterial surface assembly will therefore impact virtually all areas of pathogenesis research and inform the development of new treatments for infections. Although some aspects of cell surface assembly can be inferred from studies of non-pathogenic organisms, results from the models will never be entirely predictive. Departures from the model are likely to be especially pronounced for pathogens like Streptococcus pneumoniae (Sp) that adopt a different (ovoid) morphology and grow via distinct mechanisms from rod-shaped organisms like Escherichia coli and Bacillus subtilis where studies of cell surface assembly have traditionally been investigated. Sp is a major cause of life-threatening disease in young children and older adults, and the incidence of drug-resistant infections with this organism is on the rise. The efficacy of the polyvalent Sp vaccine is also declining due to the emergence of strains with altered surface polysaccharides that escape vaccine-induced immunity. It is therefore important to identify new ways of disabling Sp growth. To do so, we have initiated a program to investigate cell surface assembly in Sp that leverages the joint expertise of the Rudner and Bernhardt laboratories in cell wall biogenesis, gram-positive biology, microscopy, biochemistry, and genetics. Importantly, our approach is not limited to the characterization of homologs of well-studied cell morphogenesis factors from the rod-shaped model organisms. Instead we are taking advantage of forward genetic screens powered by modern sequencing methods to discover new players and biological mechanisms involved in Sp growth. Our preliminary genetic analyses have uncovered two novel regulators of the penicillin- binding proteins (PBPs) of Sp. These are the first set of factors identified in gram-positive bacteria that control the activity of these critical cell wall synthases. The first aim of the project will investigate the mechanism by which these factors modulate PBP activity and connect the function of these enzymes with other components of the morphogenetic system. In addition to controlling PBP activity, proper surface assembly also requires the regulation of enzymes that cleave the cell wall. The factors governing the activity of these enzymes are poorly understood in all bacteria. Our second aim will build on promising results where we have identified a regulatory role for surface polymers called lipoteichoic acids (LTAs) in controlling the activity of the cell wall hydrolase LytA responsible for Sp cell lysis following beta-lactam treatment. Overall, our results promise to uncover new ways of either blocking cell wall assembly or triggering autolysis for therapeutic development.