Characterization of pneumococcal secretion chaperones required for virulence

致病力所需的肺炎球菌分泌物伴侣的特性 肺炎链球菌是一种革兰氏阳性病原体，通过空气中的飞沫和 在人类鼻咽部定居，在那里无症状携带是侵袭性疾病的先决条件。S. 肺炎是一个重大的健康威胁，在全球范围内造成的死亡人数比任何其他传染病都多。在……里面 肺炎链球菌要定植并转变为侵袭性感染，细菌依赖于 许多毒力因子的阐述，这些毒力因子通过细菌膜转运，并注定要 附着在细胞壁上或分泌到宿主体内。尽管分泌蛋白在人体内的重要作用 细菌的发病机制，对以下调节蛋白质活性的机制知之甚少 革兰氏阳性菌的膜转位。我们实验室鉴定了分泌伴侣PrsA2 在革兰氏阳性细菌中，单核细胞增生性李斯特菌(Lm)是毒力所必需的，并出现在 需要适当的折叠和分泌一些毒力因子。我的研究已经 重点研究了LM的两个PRSA等位基因：prsA1和prsA2，这两个等位基因都具有肽基-Pro异构酶(PPIase) 除了折叠酶结构域之外，还有其他结构域。我们解开了Lm PrsA1的晶体结构，我破译了 PrsA1和PrsA2的结构特征有助于生物体中的PPIase和伴侣活性。我 还确定了一些PRSA活性在物种间广泛保守，而另一些则是 非常具体。我们最近解决了肺炎链球菌的晶体结构，我将使用这个结构 为了完成我的一些研究目标，以确定控制分泌物活动的机制 肺炎链球菌的毒力因子。肺炎链球菌分泌中心蛋白的表面都暴露了 蛋白质：PRSA伴侣、HtrA蛋白酶/伴侣和slrA PPIase。我假设在主持期间 感染、肺炎链球菌PrSA、htrA和slrA调节分泌物的适当折叠、稳定和活性 有助于定植和致病的蛋白质。此外，表面暴露的PRSA、HtrA和 SLRA是潜在的有吸引力的药物靶点，因为抑制可能会增加抗生素的敏感性，而 减少毒力因子的分泌。为了在指导的K99阶段实现我的研究目标，我 我将与我的导师南希·弗雷塔格博士密切合作，她是革兰氏阳性菌领域的专家 致病机制和我的合作者唐·莫里森博士，他是肺炎链球菌领域的专家 分子遗传学和生物学。通过利用蛋白质组分析技术的进步，这 获奖将使我能够建立一个研究计划，长期目标是破译 革兰氏阳性肺炎链球菌毒力因子的分泌与调控机制 这也可能与其他重要的革兰氏阳性病原体有广泛的相关性。

Characterization of pneumococcal secretion chaperones required for virulence Streptococcus pneumoniae is a Gram-positive pathogen that spreads through airborne droplets and colonizes the human nasopharynx where asymptomatic carriage is a prerequisite for invasive disease. S. pneumoniae is a significant health threat, globally causing more deaths than any other infectious disease. In order for S. pneumoniae to colonize and transition into an invasive infection, the bacterium relies on the elaboration of many virulence factors that are translocated across the bacterial membrane and destined for attachment to the cell wall or secretion into the host. Despite the pivotal importance of secreted proteins in bacterial pathogenesis, little is known about the mechanisms that regulate protein activity following membrane translocation in Gram-positive bacteria. Our laboratory identified the secretion chaperone PrsA2 in the Gram-positive bacterium Listeria monocytogenes (Lm) which is essential for virulence, and appears to be required for the proper folding and secretion of a number of virulence factors. My research has focused on the two prsA alleles of Lm: prsA1 and prsA2 that both have peptidyl-prolyl isomerase (PPIase) domains in addition to a foldase domain. We solved the crystal structure of Lm PrsA1 and I deciphered how structural features of PrsA1 and PrsA2 contribute to PPIase and chaperone activities in the organism. I have also determined that some PrsA activities are broadly conserved between species while others are highly specific. We recently solved the crystal structure of S. pneumoniae PrsA and I will use this structure to accomplish some of my research objectives to define the mechanisms that govern activity of secreted virulence factors in S. pneumoniae. Central to S. pneumoniae protein secretion are the surface exposed proteins: PrsA chaperone, HtrA protease/chaperone, and SlrA PPIase. I hypothesize that during host infection, S. pneumoniae PrsA, HtrA, and SlrA regulate proper folding, stabilization, and activity of secreted proteins which contribute to colonization and pathogenesis. In addition, surface exposed PrsA, HtrA and SlrA are potentially attractive drug targets because inhibition may increase antibiotic susceptibility while reducing virulence factor secretion. To implement my research objectives during the mentored K99 phase, I will work closely with my mentor Dr. Nancy Freitag who is an expert in the field of Gram-positive pathogenesis and my collaborator Dr. Don Morrison who is an expert in the field of S. pneumoniae molecular genetics and biology. By taking advantage of advances in proteomic analytical techniques, this award will enable me to establish a research program with the long-term objective of deciphering the mechanisms of virulence factor secretion and regulation in the Gram-positive pathogen S. pneumoniae which will also likely have broad relevance to other important Gram-positive pathogens.