Chlamydomonas Telomere Function: A Telomere Binding Protein and its Gene

端粒是染色体末端的特化结构， 对染色体的复制和维持至关重要。 端粒由高度重复的DNA和蛋白质组成， 与DNA相互作用。 莱茵衣藻端粒 重复序列（T4 AG 3）n与端粒重复基序一致 （TnAG 3），其中在脊椎动物中n=2，在植物中n=3，并且在 衣原体 来自酵母和纤毛虫的端粒DNA 研究广泛;它是非常G-丰富，在体外，G-链 容易折叠成G-G碱基配对的DNA结构， 异常稳定。 梭莱茵衣藻端粒DNA不富含G， 并且，虽然G链可以折叠成G-G碱基配对结构， 这些结构不稳定。 衣原体是一种单细胞 可以用经典和分子生物学方法研究的模式生物 遗传学和有规律的端粒重复序列。 一 蛋白，衣原体G链端粒结合蛋白（CGTBP）， 特异性结合C.莱因哈德G链端粒 重复序列T4 AG 3已经被鉴定，并且编码 该活动已被克隆。 将对CGTBP基因进行测序 并将其推导的编码序列与已知蛋白质进行比较， 序列的CGTBP将进行生化分析， 将通过免疫显微镜定位在细胞中。 转录物 和/或通过细胞监测蛋白质积累 周期 CGTBP水平改变的细胞表型 将通过用以下物质转化衣原体细胞来研究： CGTBP基因在有义或反义方向的调控下 受监管的发起人。 %%% 在真核细胞中，遗传信息由DNA编码， 它与相关的蛋白质一起被包装成一种叫做 染色体 染色体有高度特化的区域， 它们的线性末端，称为端粒，对DNA至关重要 复制，并且可能在细胞周期中具有额外的功能。 这些区域含有特征性的串联重复DNA 序列和蛋白质与那些重复的 序列的 对这些端粒蛋白知之甚少。 这个项目将提供大量的结构信息 关于一个这样的端粒蛋白，并有可能提供 关于其功能的信息。

Telomeres, the specialized structures at chromosome ends, are essential for the replication and maintenance of chromosomes. Telomeres are composed of highly repetitive DNA and proteins that interact with thtat DNA. The Chlamydomonas reinhardtii telomere repeat sequence, (T4AG3)n, conforms to the telomere repeat motif (TnAG3) where n=2 in vertebrates, n=3 in plants, and n=4 in Chlamydomonas. The telomere DNA from yeasts and ciliates has been studied extensively; it is very G-rich and, in vitro, the G-strand readily folds into G-G base paired DNA structures that are unusually stable. The C. reinhardtii telomere DNA is not G-rich, and, while the G-strand can fold into G-G base paired structures, these structures are not stable. Chlamydomonas is a unicellular model organism that can be sstudied using classical and molecular genetics and that has regular telomere repeat sequences. A protein, Chhlamydomonas G-strand telomere binding protein (CGTBP), that binds specifically to the C. reinhardtii G-strand telomere repeat sequence T4AG3 has been identified and a gene that encodes this activity has been cloned. The CGTBP gene will be sequenced and its deduced coding sequence will be compared to known protein sequences. CGTBP will be analyzed biochemically and the protein will be localized in the cell by immunomicroscopy. Transcript and/or protein accumulation will be monitored thtrough the cell cycle. The phenotypes of cells that have altered levels of CGTBP will be studied by transformation of Chlamydomonas cells with the CGTBP gene in the sense or antisense orientation under the control of regulated promoters. %%% In eukaryotic cells, the genetic information is encoded by DNA, which is packaged with associated proteins into structures called chromosomes. The chromosomes have highly specialized regions at their linear ends, called telomeres, which are essential for DNA replication, and may have additional functions in the cell cycle. These regions contain characteristic tandemly repeated DNA sequences and proteins which interact with those repeated sequences. Very little is known about these telomeric proteins. This project will provide a great deal of structural information about one such telomeric protein, and has the potential to provide information about its function also.