The opportunist Candida albicans: yeast proliferation and nutritional signaling

描述（由申请人提供）：本提案的目的是确定C.白念珠菌酵母和菌丝，用于控制增殖，以及用于通过雷帕霉素途径的靶向响应营养信号传导。在以前的工作中，我们确定了一个调节菌丝到酵母形态发生，Pes1。然而，该基因的同源物在所有其他研究的真核生物中是必不可少的，C。白色念珠菌菌丝在其耗尽期间继续健壮地生长，而酵母抑制生长。我们的初步数据表明，PES1耗尽菌丝响应Tor营养信号的抑制类似于野生型，而酵母不能适当地阻止生长。因此，Pes1是正常酵母增殖和酵母对Tor抑制的正常反应所必需的。我们发现Pes1是正常水平的翻译活性标记所必需的，我们将其用于C。白色念珠菌我们还发现它是细胞周期从G1期进展到S期所必需的。由于Pes1定位在细胞类型之间以及在活性和抑制的Tor信号状态之间存在差异，我们推断其一些蛋白质相互作用伴侣在这些不同的条件下不同，并且初步的亲和纯化实验支持这一想法。我们的目标是找出 从不同的细胞类型和营养信号状态中通过亲和纯化pes1相互作用蛋白。为了测试特异于这些条件的Pes 1相互作用配偶体的生物学相关性，将进行具有相互表位和亲和标签的共免疫沉淀实验，并将确认这些蛋白质与Pes 1在同源条件下的共定位。这些Pes 1相互作用伴侣在细胞类型特异性增殖控制中的作用 将通过反向遗传方法进行研究。将使用与特定细胞器的已知标记物的共定位来确定Pes 1在酵母和菌丝中以及在TOR活性细胞与抑制细胞中的定位。Tor信号传导途径的中心节点的遗传分析将回答细胞类型特异性信号传导是途径的所有分支固有的还是对一个分支特异的问题，并且将确定PES 1与Tor营养信号传导的这些关键要素的上位性和功能关系。本研究的结果将促进我们对普遍存在的C.白色念珠菌细胞类型，酵母菌。

DESCRIPTION (provided by applicant): The objective of this proposal is to identify the mechanisms which differ between C. albicans yeast and hyphae, for control of proliferation, and for the response to nutritional signaling through the target of rapamycin pathway. In previous work we identified a regulator of hypha-to-yeast morphogenesis, Pes1. Whereas homologs of this gene are essential in all other eukaryotes studied, C. albicans hyphae continue to grow robustly during its depletion, while yeast arrest growth. Our preliminary data show that PES1-depleted hyphae respond to inhibition of Tor nutritional signaling similarly to the wild type, whil yeast fail to arrest growth appropriately. Pes1 is therefore required both for normal yeast proliferation, and for the normal response of yeast to Tor inhibition. We found Pes1 to be required for normal levels of a marker of translational activity which we adapted for use in C. albicans. We also found it to be required for progression of the cell cycle from G1 to S phase. As Pes1 localization differs between cell types and between active and inhibited Tor signaling states, we reason that some of its protein interaction partners differ between these distinct conditions, and preliminary affinity purification experiments support this idea. We aim to identify Pes1 interacting proteins by affinity purification from the distinct cell types and nutritional signaling states. To test the biological relevance of Pes1 interaction partners specific to these conditions, co- immunoprecipitation experiments with reciprocal epitope and affinity tags will be performed, and co- localization of these proteins with Pes1 in the cognate conditions will be confirmed. The role of these Pes1 interaction partners for cell-type specific proliferation control will be investigated by reverse genetic approaches. Localization of Pes1 in yeast and hyphae, and in Tor-active versus -inhibited cells will be determined using co-localization with known markers of specific organelles. Genetic analysis of central nodes of the Tor signaling pathway will answer the question whether cell-type specific signaling is intrinsic to all branches of the pathway or is specific to one branch, and will determine the epistatic and functional relationship of PES1 to these critical elements of Tor nutritional signaling. The results of this work will promote our understanding of specific proliferation control of the ubiquitous C. albicans cell type, the yeast.