Major Contribution of Transcription Initiation to 5'-end Formation of Steady-state Transcripts in Maize
Major Contribution of Transcription Initiation to 5'-end Formation of Steady-state Transcripts in Maize
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DOI：
10.1080/15476286.2018.1561604
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发表时间：
2019
期刊：
影响因子：
4.1
通讯作者：
Hai Nian
中科院分区：
文献类型：
--
作者：
Yafeng Zhang;Xiaoyu Huang;Jingyun Zou;Xun Liao;Yujun Liu;Tengxiang Lian;Hai Nian
在植物线粒体中，一些稳态转录物含有转录起始产生的初级5个末端，而另一些稳态转录物含有转录后加工产生的加工5个末端。初级和加工转录本的分化和作图对于阐明转录和转录本末端成熟的分子机制是重要的。然而，以前的努力，系统地区分这两种类型的转录在植物线粒体失败。目前认为拟南芥中大多数成熟的mRNA可能加工有5个末端。本研究采用环形RT-PCR、定量RT-PCR、RNA 5 ′-聚磷酸酶处理和北方杂交相结合的方法，成功地对玉米线粒体中的初级转录本和加工转录本进行了区分和定位。在本研究分析的35种成熟RNA和8种前体RNA中，发现约一半（21/43）具有多种亚型。总共确定了77个稳态转录本，其中47个具有初级5末端。大多数转录起始位点（126/167）位于crTA基序的下游。这些数据表明转录起始对玉米线粒体稳态转录本的5 ′端形成有重要贡献。此外，定位结果表明，玉米线粒体中的成熟RNA末端在反式剪接之前就已经形成，C→U RNA编辑伴随着反式剪接和转录物末端的形成。
In plant mitochondria, some steady-state transcripts contain primary 5ʹ ends derived from transcription initiation, while the others have processed 5ʹ termini generated by post-transcriptional processing. Differentiation and mapping of the primary and processed transcripts are important for unraveling the molecular mechanism(s) underlying transcription and transcript end maturation. However, previous efforts to systematically differentiate these two types of transcripts in plant mitochondria failed. At present, it is considered that the majority of mature mRNAs may have processed 5ʹ ends in Arabidopsis. Here, by combination of circular RT-PCR, quantitative RT-PCR, RNA 5ʹ-polyphosphatase treatment and Northern blot, we successfully discriminated and mapped the primary and processed transcripts in maize mitochondria. Among the thirty-five mature and eight precursor RNAs analyzed in this study, about one half (21/43) were found to have multiple isoforms. In total, seventy-seven steady-state transcripts were determined, and forty-seven of them had primary 5ʹ ends. Most transcription initiation sites (126/167) were downstream of a crTA-motif. These data suggested a major contribution of transcription initiation to 5ʹ-end formation of steady-state transcripts in maize mitochondria. Moreover, the mapping results revealed that mature RNA termini had largely been formed before trans-splicing, and C→U RNA editing was accompanied with trans-splicing and transcript end formation in maize mitochondria.