AIDS Opportunistic Pathogens/Fungal Cell Wall Drug Targets

描述(申请人提供)：口腔念珠菌病是艾滋病毒感染的一个标志。三分之一的艾滋病毒血清阳性患者和90%的艾滋病患者会出现口咽部念珠菌病。很少有抗真菌药物可用于治疗，使问题复杂化的是，一些种类的念珠菌，特别是光滑念珠菌，对重要的三唑类抗真菌药物具有天生的耐药性。这项拨款建议确定酵母细胞壁生物发生的潜在靶点，以开发新的抗真菌药物。念珠菌细胞壁是一种已被证实的药物靶点：棘球菌素类药物(默克公司的念珠菌是其中的一员)针对β-1，3-葡聚糖合成酶，并可成功地用于治疗多种念珠菌，包括白色念珠菌和光滑念珠菌。细胞壁中的另一种主要葡聚糖是β1-6葡聚糖。在生化水平上对β1-6生物合成的了解较少，尽管它通常对细胞的生存能力是必不可少的。β1-6葡聚糖的基本功能之一是使蛋白质共价交联进入细胞壁：在酿酒酵母、白色念珠菌和光滑念珠菌中，绝大多数细胞壁蛋白被称为GPI-细胞壁蛋白(或GPI-CWPs)，并通过GPI锚点的残基共价连接到β1-6葡聚糖上。 GPI-蛋白附着在细胞壁上的过程根本不是很详细。我们已经建立了分析GPI-蛋白质与细胞壁交联的试剂，并建议使用这些试剂来鉴定和分析GPI-CWP加工和与β1-6葡聚糖交联受损的酿酒酵母突变株。具体地说，我们正在产生一系列已知或预测参与GPI-CWP生物发生的基因的温度敏感等位基因。我们将利用这些温度敏感的突变株来分析GPI-CWP交联途径中的中间产物，以更准确地确定这些基因在GPI-CWP成熟和交联中的作用。 酵母细胞壁对酵母的活性至关重要，而GPI-CWP功能对细胞壁的完整性是必不可少的。鉴定负责GPI-CWP交联的酶将允许化疗靶向真菌特定的、基本的和已被证实的新的抗真菌疗法的开发目标。

DESCRIPTION (provided by applicant): Oral candidiasis is a hallmark of HIV infection. A third of HIV sero-positive and 90% of AIDS patients will present with oropharyngeal candidiasis. Few antifungal agents are available for treatment and to compound the problem, some species of Candida, notably Candida glabrata, are innately resistant to the important triazole class of antifungals. This grant proposes to identify potential targets in yeast cell wall biogenesis for development of novel antifungal agents. The Candida cell wall is a proven drug target: the echinocandin class of drugs (of which Merck's Cancidas is a member) target beta1,3 glucan synthase and can be successfully used against multiple species of Candida including Candida albicans and C. glabrata. The other major glucan in the cell wall is beta1-6 glucan. Less is understood at a biochemical level about beta1-6 biosynthesis, although it is normally essential for the viability of the cell. One of beta1-6 glucan's essential functions is to covalently crosslink proteins into the cell wall: the vast majority of cell wall proteins in S. cerevisiae and in C. albicans and C. glabrata are so called GPI-cell wall proteins (or GPI-CWPs) and are covalently attached through the remnant of the GPI anchor to beta1-6 glucan. The process by which GPI-proteins are attached to the cell wall is not understood in detail at all. We have established reagents for analyzing GPI-protein crosslinking to the cell wall and propose using these to identify and analyze mutants of S. cerevisiae in which GPI-CWP processing and crosslinking to beta1-6 glucan is compromised. Specifically, we are generating a series of temperature sensitive alleles of genes known or predicted to be involved in GPI-CWP biogenesis. We will use these temperature sensitive mutant strains to analyze intermediates in the GPI-CWP crosslinking pathway to more precisely define the role of these genes in the maturation and crosslinking of GPI-CWPs. The yeast cell wall is essential for yeast viability, and GPI-CWP function is essential to cell wall integrity. Identification of the enzymes responsible for GPI-CWP crosslinking will allow chemotherapeutic targeting of a fungal specific, essential and proven target for development of new antifungal therapy.