Downregulation of the essential Trypanosoma brucei La protein affects accumulation of elongator methionyl-tRNA
Downregulation of the essential Trypanosoma brucei La protein affects accumulation of elongator methionyl-tRNA
复制标题
DOI：
10.1016/j.molbiopara.2005.06.006
复制
发表时间：
2005-11-01
影响因子：
1.5
通讯作者：
Ullu, E
中科院分区：
文献类型：
--
作者：
Arhin, GK;Shen, SY;Ullu, E
寄生原生动物布氏锥虫编码典型的真核小细胞质（sc）和核（sn）RNA的完整互补。这些包括tRNA、5S RNA、7SL RNA和U1、U2、U3、U4、U 5和U6 snRNA。后者参与RNA加工的不同方面，即反式和顺式剪接（U1，U2，U4，U 5和U6）或前rRNA成熟（U3）。所有这些RNA都由RNA聚合酶（pol）III转录[1]，与大多数其他真核生物相反，其中U1，U2，U3，U4和U 5 snRNA由RNA pol II转录。唯一已知的由pol II转录的锥虫snRNA是剪接前导（SL）RNA [2]，其通过反式剪接将SL提供给所有mRNA。新合成的pol III转录物以一串尿苷酸结束，这些尿苷酸随后被修剪以产生成熟的3′-末端。合成后不久，这些寡聚（U）延伸被La蛋白结合，La蛋白是一种核磷蛋白，在整个真核生物进化过程中一直保守，并保护新生pol III RNA的3′端免受核酸酶降解[3]。在酿酒酵母中，La还与RNA聚合酶II转录物（如U1、U2、U3、U4和U 5 snRNA）形成复合物，这些snRNA由于初级转录物的部分加工而终止于聚尿苷束[4，5]。对于pretRNA，需要La来内切核酸去除3 '尾部[6]，调节5'末端加工[7]，并且作为RNA伴侣，帮助某些pre-tRNA的正确折叠[8]。在U snRNA的情况下，S.酿酒酵母
The parasitic protozoa Trypanosoma brucei encodes a full complement of typical eukaryotic small cytoplasmic (sc) and nuclear (sn) RNAs. These include tRNAs, 5S RNA, 7SL RNA and U1, U2, U3, U4, U5 and U6 snRNAs. The latter are involved in different aspects of RNA processing, namely trans-and cis-splicing (U1, U2, U4, U5 and U6), or pre-rRNA maturation (U3). All these RNAs are transcribed by RNA polymerase (pol) III [1], in contrast to most other eukaryotes where U1, U2, U3, U4 and U5 snRNAs are transcribed by RNA pol II. The only known trypanosome snRNA transcribed by pol II is the spliced leader (SL) RNA [2], which donates the SL to all mRNAs via trans-splicing. Newly synthesized pol III transcripts end in a string of uridylates that are subsequently trimmed to generate the mature 3′-end. Soon after synthesis these oligo (U) extensions are bound by the La protein, a nuclear phosphoprotein that has been conserved throughout eukaryotic evolution and protects the 3′-end of nascent pol III RNAs from nuclease degradation [3]. In Saccharomyces cerevisiae, La also forms a complex with RNA polymerase II transcripts such as U1, U2, U3, U4 and U5 snRNAs that end in a polyuridine tract as a result of partial processing of the primary transcripts [4, 5]. For pretRNAs, La is required for the endonucleolytic removal of the 3′ trailer [6], for modulation of 5′-end processing [7] and, as an RNA chaperone, for assisting the correct folding of certain pre-tRNAs [8]. In the case of the U snRNAs, the S. cerevisiae