Canaday J, Tessier L H, Imbault P, Paulus F
Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Strasbourg, France.
Mol Genet Genomics. 2001 Mar;265(1):153-60. doi: 10.1007/s004380000403.
We have cloned and analyzed alpha-, beta- and gamma-tubulin genes from Euglena gracilis. The gamma-tubulin genes are 6-10 times longer than the alpha- and beta-tubulin genes, owing to the presence of numerous introns. These introns are all of the conventional type, whereas the alpha- and beta-tubulin genes contain both conventional and non-conventional introns. This is the first time that both types of introns have been found in the same gene. In the E. gracilis genome there are two genes for each tubulin, but the level of gamma-tubulin mRNA is 60 times lower than that of alpha- and beta-tubulin RNAs. The distinctive structure of gamma-tubulin genes prompted us to investigate the maturation of its pre-mRNA. We show that trans-splicing occurs before the cis-splicing of the first intron of the pre-mRNA and that polyadenylation occurs after the cis-splicing of the last intron of the pre-mRNA. We propose that mRNA processing is likely to play a role in regulating the amounts of different tubulins in E. gracilis.
我们已经克隆并分析了纤细裸藻的α-、β-和γ-微管蛋白基因。由于存在大量内含子，γ-微管蛋白基因比α-和β-微管蛋白基因长6到10倍。这些内含子均为常规类型，而α-和β-微管蛋白基因既包含常规内含子也包含非常规内含子。这是首次在同一基因中发现这两种类型的内含子。在纤细裸藻基因组中，每种微管蛋白都有两个基因，但γ-微管蛋白mRNA的水平比α-和β-微管蛋白RNA的水平低60倍。γ-微管蛋白基因的独特结构促使我们研究其前体mRNA的成熟过程。我们发现反式剪接发生在mRNA前体第一个内含子的顺式剪接之前，而聚腺苷酸化发生在mRNA前体最后一个内含子的顺式剪接之后。我们认为mRNA加工可能在调节纤细裸藻中不同微管蛋白的数量方面发挥作用。
