Genetic Control of Nutrition Starvation in Yeast

描述（由申请人提供）：本研究的目的是确定酿酒酵母中控制丝状结构的调控回路，丝状结构是致病和非致病真菌的关键形态发生。与S288c的参考文库相比，我们在酿酒酵母Sigma菌株中的缺失文库能够全面评估导致两种不同实验室菌株中相同突变的不同丝化和活力表型的遗传机制。这个问题与人类遗传学家在研究复杂疾病特征的遗传能力时所面临的问题是一样的。对真菌粘附医疗器械的能力至关重要的成丝/粘附特性的分析表明，由IME4基因催化的mRNA的m6A修饰是一个关键的转录后事件，控制着进入成丝或减数分裂途径的决定。实验将确定这种m6A修饰的功能，以及标记的消失是由于去甲基化还是特异性信使降解。在一个菌株（Sigma）中激活丝化基因的信号转导途径（丝化MAPK途径，fMAPK）在另一个菌株（S288c）中是不需要的，它已经进化出了绕过该途径必要性的多态性。对这种可选择的丝状通路的分析将揭示这些多态性发展的潜在网络。特别重要的是两个顺式作用的非编码rna， PWR1和ICR1，它们在Sigma中被证明是一个顺式作用的开关，控制邻近的FLO11基因的表达，这是成丝所必需的。实验旨在确定这些非编码rna是否参与S288c中FLO11的表达，其中一组不同的反式作用因子激活FLO11。这些实验将揭示物种内普遍存在的ncRNA调控。我们的全基因组比较还发现了条件必需基因，这些基因的功能在一个菌株的生存能力中是必需的，而不是必需的

DESCRIPTION (provided by applicant): The goal of this research is to determine the regulatory circuits in S. cerevisiae that control filamentation, a key morphogenetic even in pathogenic and non-pathogenic fungi. Our deletion library in the S. cerevisiae Sigma strain, when compared with the reference library in S288c, enables a comprehensive assessment of the genetic mechanisms leading to different filamentation and viability phenotypes for the same mutation in two different laboratory strains. This problem is the same one confronting human geneticists tackling the heritability of complex disease traits. The analysis of the filamentation/adhesion trait, which is important for the ability of fungi to adhere to medical devices, revealed that a m6A modification of mRNA, catalyzed by the IME4 gene, is a key post-trancriptional event that controls the decision to enter the filamentation or meiotic pathway. Experiments will determine the function of this m6A modification and whether the disappearance of the mark is due to demethylation or specific messenger degradation. The signal transduction pathway (the filamentation MAPK pathway, fMAPK) that activates filamentation genes in one strain (Sigma) is not required in the other (S288c), which has evolved polymorphisms that bypass the necessity for this pathway. The analysis of this alternative filamentation pathway will reveal the underlying network within which these polymorphisms develop. Of particular importance are two cis-acting non-coding RNAs, PWR1 and ICR1, that have been shown in Sigma to be a cis-acting toggle controlling the expression of the adjacent FLO11 gene, which is required for filamentation. Experiments are designed to determine whether these non-coding RNAs are involved in FLO11 expression in S288c, where a different set of trans- acting factors activate FLO11. These experiments will shed new light on the ubiquity of ncRNA regulation within a species. Our genome-wide comparison also identified conditionally essential genes, genes whose function is required for viability in one strain but not the other. The analysis of the genetic differences that lead to suppression of lethality has raised the possibility that extra-chromosomal elements (mitochondrial DNA) and dsRNA interact with chromosomal polymorphisms to cause variation. The discovery of these nucleo/cytoplasmic interactions adds an unanticipated dimension to the analysis of complex traits.