DNA Repair Mechanisms in Candida albicans

描述（由申请人提供）： DNA修复尚未在人类病原体白色念珠菌中进行研究，尽管许多观察结果表明临床分离株之间存在广泛的基因组变异性。这种变异性与多种基因组改变相关，包括缺失、易位、倍性变化以及染色体或部分染色体的丢失。这些变化的适应性，毒力和宿主中的真菌的生长的关系是不确定的，但糖的利用和耐药性已在体外与非整倍体相关。同源重组[HR]和非同源末端连接[NHEJ]应该是DNA修复中的重要组成部分，以确保这些基因组改变的保真度。我们对HR途径的Rad52p和NHEJ途径的Lig4p的初步研究表明，这两种蛋白除了在C.白色念珠菌这一事实沿着该病原体令人惊讶的基因组变异性，表明S. cerevisiae和C.白色念珠菌为了理解人力资源和NHEJ在这个有机体中的作用，我们提出了四个具体目标。具体目标1包括在两个途径中的每一个中构建新的突变体，NHEJ中的HDF1和HR中的RAD59。在具体目标2中，我们将完成对PIF1和RRM3的分析，这两个蛋白质是从与Lig4p相互作用的双杂交筛选中鉴定的。HR和NHEJ通路蛋白在DNA修复和形态发生中的作用是具体目标3的焦点。此外，微阵列分析将被用来确定上调和下调基因在选定的突变体的C。白细胞相比，野生型细胞。最后，目的4是评估几种基因缺失突变体在念珠菌病发病机制中的作用。我们建议使用三种小鼠念珠菌病模型，包括侵入性，口腔和阴道模型，以确定这些基因在毒力中的位点特异性作用，以评估毒力。总之，我们的研究将提供关键信息的贡献，DNA修复的适应，生长，变异性和毒力的C。白色念珠菌

DESCRIPTION (provided by applicant): DNA repair has not been studied in the human pathogen Candida albicans in spite of numerous observations that suggest extensive genomic variability among clinical isolates. This variability has been associated with a variety of genomic alterations that include, deletions, translocations, ploidy changes, as well as loss of chromosomes or parts of chromosomes. The relationship of these changes to adaptation, virulence, and growth of the fungus in the host is uncertain, but sugar utilization and drug resistance have been correlated in vitro with aneuloploidy. Homologous recombination [HR] and non-homologous end-joining [NHEJ] should be important components in DNA repair to ensure the fidelity of these genomic alterations. Our preliminary studies with Rad52p of the HR and Lig4p of the NHEJ pathways suggest that both proteins provide growth functions in addition to DNA repair in C. albicans. This fact along with the surprising genomic variability of this pathogen suggest differences between the DNA repair pathways of S. cerevisiae and C. albicans. To understand the roles of HR and NHEJ in this organism, we propose four specific aims. Specific aim 1 includes the construction of new mutants in each of the two pathways, HDF1 in NHEJ and RAD59 in HR. In specific aim 2, we will complete our analysis of PIF1 and RRM3, two proteins identified from a two-hybrid screen that interact with Lig4p. The role of HR and NHEJ pathway proteins in DNA repair and morphogenesis is the focus of specific aim 3. In addition, microarray analysis will be used to identify up and down regulated genes in selected mutants of C. albicans when compared to wild type cells. Finally, aim 4 is designed to evaluate the role of several gene deleted mutants in the pathogenesis of candidiasis. We propose to use three mouse models of candidiasis to evaluate virulence, including, invasive, oral, and vaginal models so as to identify a site-specific role of these genes in virulence. In summary, our studies will provide critical information on the contribution of DNA repair to the adaptation, growth, variability and virulence of C. albicans.