Manger I D, Boothroyd J C
Dept. of Microbiology & Immunology, Stanford University Medical Center, CA 94305-5124, USA.
Mol Biochem Parasitol. 1998 Nov 30;97(1-2):1-11. doi: 10.1016/s0166-6851(98)00118-2.
Gene expression in trypanosomes is controlled at the level of pre-mRNA maturation via trans-splicing and polyadenylation and through changes in mRNA stability. To identify the trans- acting factors involved in this regulation, we have used a degenerate PCR approach to clone genes encoding the RNA recognition motif (RRM) consensus. We have identified a single-copy gene encoding a protein (designated RRM1) which contains three consensus RRM motifs, two tandem copies of a retroviral gag-like CCHC 'zinc finger' and an arginine-serine (RS) rich region. Western blotting indicates that RRM1 is expressed in both procyclic and bloodstream-form trypanosomes and has an apparent mobility on SDS-PAGE of ca. 70 Kd. RRM1 is localized in the trypanosome nucleus in substructures which may be functionally analogous to the 'speckles' associated with cis-splicing in higher eukaryotic cells. The structure of RRM1, its pattern of expression and its intracellular location suggest that it may play a role in trans-splicing.
锥虫中的基因表达是通过反式剪接和聚腺苷酸化在mRNA前体成熟水平以及通过mRNA稳定性的变化来控制的。为了鉴定参与这种调控的反式作用因子，我们使用了简并PCR方法来克隆编码RNA识别基序（RRM）共有序列的基因。我们鉴定出一个单拷贝基因，其编码一种蛋白质（命名为RRM1），该蛋白质包含三个共有RRM基序、两个逆转录病毒gag样CCHC“锌指”的串联拷贝以及一个富含精氨酸-丝氨酸（RS）的区域。蛋白质免疫印迹表明RRM1在原循环型和血流型锥虫中均有表达，并且在SDS-PAGE上的表观迁移率约为70 Kd。RRM1定位于锥虫细胞核中的亚结构中，这些亚结构在功能上可能类似于与高等真核细胞顺式剪接相关的“斑点”。RRM1的结构、其表达模式及其细胞内定位表明它可能在反式剪接中发挥作用。
