Multiple Calmodulin-Like Proteins in a Unicellular Eukaryote

单细胞真核生物中的多种钙调蛋白样蛋白

• 批准号: 9005589
• 负责人: Chandler Fulton
• 金额: $ 27.99万
• 依托单位: Brandeis University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-08-01 至 1994-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9005589&HistoricalAwards=false
• 关键词: Multiple; Calmodulin; Like; Proteins; Unicellular

The dramatic cell differentiation undergone by Naegleria gruberi, from amoebae to flagellates, is unique as a model system in the rapidity, synchrony, reproducibility, homogeneity, and Accessibility of a major phenotypic change. Differentiation-specific molecules synthesized during this change include two calmodulins, one that becomes localized in the flagella and the other that remains in the cell body. Cloning and sequencing of the single flagellar calmodulin gene revealed provocative structural features that may be implicated in regulation of its programmed transcription, in the stability of its mRNA, and in the localization of its protein. In order to test these possibilities, and to make this system advantageous for other studies, this laboratory is working vigorously to obtain DNA-mediated transformation of Naegleria. In addition, initial searches for DNA clones to cell body calmodulin have led to the discovery of two additional calcium-binding protein genes expressed during differentiation. One encodes a calcineurin B-like protein; the other and undefined calcium-binding protein whose gene sequence is related to flagellar calmodulin DNA but which is expressed earlier in differentiation. The goals of this research are to find the calmodulin-2 gene and to dissect these multiple calmodulin-like proteins in Naegleria, while continuing to seek DNA-mediated transformation in this remarkable organism. The unicellular eukaryote, Naegleria gruberi reproduces as amoebae. If conditions are suitable, the amoebae undergo a rapid, dramatic differentiation into lively, swimming flagellates with a fixed, streamlined body contour. The flagellates are temporary, do not reproduce, and eventually revert back to amoebae. The long-term goal of this research is to elucidate the sequence of events (from environmental trigger, through programmed changes in gene expression, to localization of differentiation-specific gene products) that underlie these differentiation events. The current goals of this project are to identify and characterize genes for proteins involved in the regulation of cellular functions by calcium. Since the genes for these regulatory molecules are expressed differently at different stages of the differentiation process in different parts of the organism, it is likely that they represent an important link in this chain of events.

从变形虫到鞭毛虫，Naegleria gruberi经历了戏剧性的细胞分化，在主要表型变化的快速性、同步性、重复性、同质性和可及性方面是独一无二的模式系统。在这种变化过程中合成的分化特异性分子包括两个钙调蛋白，一个定位于鞭毛，另一个保留在细胞体中。单个鞭毛钙调蛋白基因的克隆和测序揭示了具有刺激性的结构特征，这些特征可能与其程序性转录的调节、其mRNA的稳定性和其蛋白质的定位有关。为了验证这些可能性，并使该系统有利于其他研究，本实验室正在努力获得DNA介导的Naegleria转化。此外，对细胞体钙调蛋白的DNA克隆的初步搜索导致发现了另外两个在分化过程中表达的钙结合蛋白基因。一种编码类钙调神经磷酸酶B蛋白，另一种未知的钙结合蛋白，其基因序列与鞭毛钙调蛋白DNA有关，但在分化早期表达。本研究的目标是发现钙调蛋白-2基因，并在Naegleria中剖析这些多个钙调蛋白样蛋白，同时继续在这种非凡的生物中寻找DNA介导的转化。单细胞真核生物格氏奈格勒以阿米巴虫的形式繁殖。如果条件合适，变形虫会经历快速、戏剧性的分化，变成活泼的、游动的鞭毛，具有固定的流线型身体轮廓。鞭毛是暂时的，不会繁殖，最终会恢复成阿米巴。这项研究的长期目标是阐明这些分化事件背后的事件序列(从环境触发，到基因表达的程序性变化，再到分化特异性基因产物的定位)。该项目目前的目标是识别和表征参与钙调节细胞功能的蛋白质的基因。由于这些调控分子的基因在生物体不同部位分化过程的不同阶段表达不同，它们很可能代表了这一事件链中的重要一环。