A Novel Cholesterol-Dependent Cytolysin Receptor

一种新型胆固醇依赖性溶细胞素受体

• 批准号: 7007618
• 负责人: Rodney K. Tweten
• 金额: $ 32.19万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-15 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7007618
• 关键词: SDS polyacrylamide gel electrophoresis; Streptococcus; bacterial proteins; bacterial toxins; binding sites; cholesterol; clinical research; cytolysins; flow cytometry; ligands; polymerase chain reaction; pore forming protein; protein protein interaction; receptor; receptor binding

DESCRIPTION (provided by applicant): The cholesterol-dependent cytolysins (CDCs) are a large family of related bacterial toxins produced by over 20 species of Gram-positive pathogenic bacteria. Several CDCs have been shown to contribute to the pathogenic mechanisms of these bacterial species. The CDCs are produced as soluble proteins that oligomerize into large pore-forming complexes on the surface of cholesterol-containing membranes. The presence of membrane cholesterol is required for the CDC pore-formation and is a hallmark of the CDCs. For over three decades the receptor for the CDCs was generally accepted as cholesterol but recent studies show that it is necessary for the prepore to pore conversion of the CDCs, an event that is downstream of membrane binding. Therefore, the longstanding dogma that the CDCs use cholesterol as their receptor appears less plausible. We have now determined that at least one member of the CDC family, intermedilysin (ILY) from Streptococcus intermedius, utilizes the GPI-anchored human CD59 (hCD59) as its receptor. Based on preliminary studies we hypothesize that 1) ILY domain 4 contains the residues required for binding to and specificity for hCD59, 2) the region and residues of hCD59 recognized by human complement proteins C8 and C9 also comprises the hCD59 binding site for ILY, and 3) ILY disengages from its receptor prior to pore formation. This proposal is designed to examine the interaction of ILY with hCD59 and to map out the structural domains of both ILY and hCD59 that are involved in this ligand-receptor interaction. The interaction of ILY with hCD59 will also be examined at various stages of the cytolytic mechanism to determine if the toxin disengages from receptor during the assembly of its pore complex. These hypotheses will be addressed in three specific aims that will establish the location of the binding sites on both hCD59 and ILY and will determine whether ILY undocks from receptor during the assembly of the pore-forming complex. The results of these studies will provide a basis for investigations of a new and significant aspect of the CDCs previously unavailable to the study of these toxins. The discovery and study of a CDC receptor will have a significant impact on the study of CDCs and will alter our perception of their role in a large number of diseases caused by a wide variety of Gram-positive pathogens.

描述（由申请人提供）：胆固醇依赖性溶细胞素（CDC）是由 20 多种革兰氏阳性病原菌产生的一大类相关细菌毒素。一些 CDC 已被证明有助于这些细菌物种的致病机制。 CDC 作为可溶性蛋白质产生，在含胆固醇膜的表面寡聚成大的成孔复合物。膜胆固醇的存在是 CDC 孔形成所必需的，并且是 CDC 的标志。三十多年来，CDC 的受体普遍被认为是胆固醇，但最近的研究表明，CDC 的前孔到孔的转化是必要的，这是膜结合下游的事件。因此，疾病预防控制中心使用胆固醇作为受体的长期教条似乎不太合理。我们现在已经确定，CDC 家族的至少一个成员，即来自中间链球菌的 intermedilysin (ILY)，利用 GPI 锚定的人 CD59 (hCD59) 作为其受体。基于初步研究，我们假设 1) ILY 结构域 4 包含与 hCD59 结合并具有特异性所需的残基，2) 人补体蛋白 C8 和 C9 识别的 hCD59 区域和残基也包含 ILY 的 hCD59 结合位点，并且3) ILY 在孔形成之前与其受体脱离。该提案旨在检查 ILY 与 hCD59 的相互作用，并绘制出参与这种配体-受体相互作用的 ILY 和 hCD59 的结构域。还将在细胞溶解机制的各个阶段检查 ILY 与 hCD59 的相互作用，以确定毒素是否在其孔复合物组装过程中从受体脱离。这些假设将在三个具体目标中得到解决，这些目标将确定 hCD59 和 ILY 上的结合位点的位置，并将确定 ILY 是否在成孔复合物组装过程中与受体脱离。这些研究的结果将为 CDC 的一个新的重要方面的调查提供基础，而这些方面以前无法用于研究这些毒素。 CDC受体的发现和研究将对CDC的研究产生重大影响，并将改变我们对其在多种革兰氏阳性病原体引起的大量疾病中的作用的看法。