The role of the CCAAT-binding factor in Candida albicans

描述(申请人提供)：白色念珠菌是人类最常见的真菌病原体，可引起多种皮肤和全身感染。有许多诱因导致念珠菌感染；然而，免疫功能受损的患者数量不断增加(主要是由于免疫抑制疗法和艾滋病)，导致念珠菌病的发病率急剧增加。这一事实，再加上治疗药物的有限，决定了目前的研究努力集中在阐明导致念珠菌毒力的途径和确定药物开发的新靶点上。这项研究计划的长期目标是调查真菌CCAAT结合因子的独特结构特征是否可以作为抗真菌化合物的靶标。CCAAT结合因子是一种异寡聚体转录激活子，在真核生物中高度保守；然而，在真菌中，该转录因子含有一个新的亚基(称为Hap4p)，这是其他真核生物中没有的。正是这种真菌特异性亚基与异构体复合体的其他成分的独特相互作用代表了药物开发的潜在靶点。Hap4p未能与复合体的DNA结合成分相互作用导致靶基因表达的丧失。因此，开发抑制这种真菌特异性蛋白质-蛋白质相互作用的多肽或小分子可以提供一种可行的方法来对抗真菌感染。这项研究的目标是确定CCAAT结合因子在白色念珠菌中的调节功能，并检查它在参与毒力和致病的基因调节中是否重要，作为探索其作为治疗药物靶点的潜力的第一步。拟议的研究将针对以下特定目标：1)在编码CCAAT结合因子的各个亚基的基因中产生突变并评估其表型；2)确定CCAAT结合因子是否对白念珠菌的毒力重要；以及3)剖析CCAAT结合因子的调节功能。

DESCRIPTION (provided by applicant): Candida albicans is the most frequently encountered fungal pathogen in humans, and is responsible for a variety of rnucocutaneous and systemic infections. There are a number of predisposing factors that contribute to Candida infections; however, the increasing number of immunocompromised patients (due primarily to imrnunosuppressive therapies and AIDS) has led to a sharp increase in the incidence of candidiasis. This fact, coupled with the limited arsenal of therapeutic agents, dictates that current research efforts focus on elucidating pathways that contribute to Candida virulence and on identifying novel targets for drug development. The long-term goal of this research program is to investigate whether a unique structural feature of fungal CCAAT-binding factors could serve as a target for antifungal compounds. The CCAAT-binding factor is a heterooligomeric transcriptional activator that is highly conserved evolutionarily in all eukaryotes; however, in fungi this transcription factor contains a novel subunit (termed Hap4p) that is not found in other eukaryotes. It is the unique interaction of this fungal-specific subunit with other components of the heteromeric complex that represents a potential target for drug development. The failure of Hap4p to interact with the DNA-binding components of the complex results in the loss of target gene expression. Thus, development of peptides or small molecules that inhibit this fungal-specific protein-protein interaction could offer a viable approach to combating fungal infections. The goal of the studies described in this proposal is to determine the regulatory function of the CCAAT-binding factor in C. albicans, and to examine whether it is important in the regulation of genes involved in virulence and pathogenesis, as the initial step toward exploring its potential as a therapeutic drug target. The proposed studies will address the following specific aims: 1) to generate mutants in the genes encoding the various subunits of the CCAAT-binding factor and evaluate their phenotypes; 2) to determine whether the CCAAT-binding factor is important for C. albicans virulence; and 3) to dissect the regulatory function of the CCAAT-binding factor.