Proulex Grayson C R, Meade Marcus J, Manoylov Kalina M, Cahoon A Bruce
Department of Natural Sciences, The University of Virginia's College at Wise, 1 College Ave., Wise, VA 24293, USA.
Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, GA 31061, USA.
Plants (Basel). 2021 Mar 18;10(3):576. doi: 10.3390/plants10030576.
Mitochondria carry the remnant of an ancestral bacterial chromosome and express those genes with a system separate and distinct from the nucleus. Mitochondrial genes are transcribed as poly-cistronic primary transcripts which are post-transcriptionally processed to create individual translationally competent mRNAs. Algae post-transcriptional processing has only been explored in (Class: Chlorophyceae) and the mature mRNAs are different than higher plants, having no 5' UnTranslated Regions (UTRs), much shorter and more variable 3' UTRs and polycytidylated mature mRNAs. In this study, we analyzed transcript termini using circular RT-PCR and PacBio Iso-Seq to survey the 3' and 5' UTRs and termini for two green algae, (Class: Chlorophyceae) and (Class: Charophyceae). This enabled the comparison of processing in the chlorophyte and charophyte clades of green algae to determine if the differences in mitochondrial mRNA processing pre-date the invasion of land by embryophytes. We report that the 5' mRNA termini and non-template 3' termini additions in resemble those of , suggesting a conservation of mRNA processing among the chlorophyceae. We also report that mRNA UTRs are much longer than chlorophytic examples, lack polycytidylation, and are polyadenylated similar to embryophytes. This demonstrates that some mitochondrial mRNA processing events diverged with the split between chlorophytic and streptophytic algae.
线粒体携带着祖先细菌染色体的残余部分，并通过一个与细胞核分离且不同的系统来表达这些基因。线粒体基因转录为多顺反子初级转录本，这些转录本在转录后进行加工，以产生单个具有翻译能力的mRNA。藻类的转录后加工仅在绿藻纲中进行过研究，其成熟mRNA与高等植物不同，没有5'非翻译区（UTR），3'UTR更短且更具变异性，并且成熟mRNA进行了多聚胞嘧啶化修饰。在本研究中，我们使用环状RT-PCR和PacBio Iso-Seq分析转录本末端，以调查两种绿藻（绿藻纲）和轮藻（轮藻纲）的3'和5'UTR及末端。这使得能够比较绿藻的绿藻纲和轮藻纲分支中的加工过程，以确定线粒体mRNA加工的差异是否早于陆生植物登陆。我们报告说，莱茵衣藻中的5'mRNA末端和非模板3'末端添加类似于小球藻，这表明绿藻纲中mRNA加工具有保守性。我们还报告说，轮藻的mRNA UTR比绿藻的例子长得多，缺乏多聚胞嘧啶化，并且与陆生植物一样进行多聚腺苷酸化。这表明一些线粒体mRNA加工事件随着绿藻和轮藻藻类的分化而发生了分歧。
