CELLULARIZATION IN ASPERGILLUS NIDULANS

构巢曲霉的细胞化

• 批准号: 2187418
• 负责人: JOHN E HAMER
• 金额: $ 19.81万
• 依托单位: PURDUE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2187418
• 关键词: Aspergillus; cell cycle; cell differentiation; cell growth regulation; fungal genetics; fusion gene; gene complementation; gene expression; gene interaction; gene mutation; histogenesis; immunocytochemistry; molecular cloning; regulatory gene; western blottings

Fungi impact human existence as opportunistic pathogens and as important industrial biocatalysts.The long term goals of this research are to provide new information on fungal cell division. Cytokinesis, is a fundamental growth process in all cells and involves the coordination of cell growth and the nuclear division cycle. Web have chosen to analyze this process in the filamentous fungus, Aspergillus nidulans. This genetically tractable eukaryotic microbe has a rich history of molecular genetic research and is a close relative of many medically and industrially important microorganisms. In A. nidulans cytokinesis occurs by the formation of crosswalls termed septa. We have shown that septum formation is an actin dependent process, temporally coordinated with mitosis. We have identified and characterized ten genes, designated sepA, B, C, D, E, G, H, I, J and K carrying temperature sensitive (ts) mutations that block cytokinesis. These cytokinesis mutants sort into three phenotypic classes. Class 1 mutants (B, C, E, I and J) appear to be involved in early steps in signalling septum formation. Class 2 mutants (A and K) may be defective in actin dependent processes such as localized cell wall growth. Class 3 mutants (D,G and H) appear to be blocked at later stages of septum formation. Together with data from physiological experiments, we have formulated a genetic model for septum formation. The sepA and sepB genes have been cloned. Finally we have identified three A. nidulans homologs of the Saccharomyces cerevisiae bud-neck filament genes encoded by the CDC3, 10, 11 and 12 genes. We have designated these loci ANFl, 2and 3. The specific goals of this proposal are to determine the specific functions of several sep genes representing the three phenotypic classes: specifically sepA, B, C, D, E and K genes. This will be done by cloning the genes and characterizing the protein products they encode with regard to expression, cellular localization and similarities to other known proteins. A series of genetic experiments will be used to assess sep gene function. These include the construction of double mutants to assess interactions between sep gene products. We have devised genetic screens to identify additional genes involved in the cellularization process. Mutants will be sought that lack septa, mis-regulate the timing of septum formation, or form precocious numbers of septa. Mutations will be constructed in the ANF genes to assess their role in cytokinesis. Finally probes developed from the above research will be used to more precisely define the phenotypic defect in the sep mutants as well as to define the temporal order of events for cytokinesis in A. nidulans. The results from our research will provide new information on fungal growth and differentiation. Due to apparent similarities to cytokinesis in animal cells, a genetic and molecular analysis of septation may elucidate the roles of regulatory or structural proteins common to both processes.

真菌将人类的存在视为机会主义病原体和重要 工业生物催化剂。这项研究的长期目标是 提供有关真菌细胞部门的新信息。细胞因子是一个 所有细胞的基本生长过程，涉及协调 细胞生长和核分裂周期。网络选择分析 在丝状真菌，曲霉尼古拉人中的这一过程。 这 遗传上可拖动的真核微生物具有丰富的分子历史 遗传研究，是许多医学上的近亲 工业重要的微生物。 在A. nidulans cytokinesis中，通过称为横墙的形成发生 隔膜。我们已经表明，隔膜形成是肌动蛋白依赖的过程， 与有丝分裂的时间协调。我们已经确定和表征 十个基因，指定为sepa，b，c，d，e，g，h，i，i，j和k携带 温度敏感（TS）突变，可阻断细胞因子。这些 细胞因子突变体分为三个表型类。 1类突变体 （b，c，e，i和j）似乎参与了发信号的早期步骤 隔膜形成。 2类突变体（A和K）在肌动蛋白中可能有缺陷 依赖过程，例如局部细胞壁生长。 3类突变体 （D，G和H）似乎在隔膜形成的后期被阻塞。 加上来自生理实验的数据，我们制定了 隔膜形成的遗传模型。 SEPA和SEPB基因已经 克隆。最后，我们确定了三个A. nidulans的同源物 Cdc3，10，cervisiae Bud-Neck丝基因酿酒酵母基因 11和12基因。我们指定了这些基因座ANFL，2和3。 该提案的具体目标是确定具体 代表三种表型类别的几个SEP基因的功能： 特别是sepa，b，c，d，e和k基因。这将通过克隆完成 基因和表征他们对蛋白质产物的特征 表达，细胞定位和与其他已知的相似性 蛋白质。一系列遗传实验将用于评估SEP基因 功能。这些包括构造双突变体以评估 SEP基因产物之间的相互作用。我们已经将基因筛选设计为 确定涉及细胞化过程的其他基因。突变体 将寻求缺乏隔膜，错误地调节隔膜的时间 形成或形成早熟的隔sa。突变将是 在ANF基因中构建以评估其在细胞因子中的作用。最后 从上述研究开发的探针将被用来精确 定义SEP突变体中的表型缺陷，并定义 A. nidulans中细胞因子事件的时间顺序。 我们研究的结果将提供有关真菌的新信息 生长与分化。由于与细胞因子的明显相似 动物细胞，分子的遗传和分子分析可能会阐明 这两个过程共有的调节或结构蛋白的作用。