Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
Nucleic Acids Res. 2022 May 20;50(9):5029-5046. doi: 10.1093/nar/gkac295.
Bacterial mRNAs have short life cycles, in which transcription is rapidly followed by translation and degradation within seconds to minutes. The resulting diversity of mRNA molecules across different life-cycle stages impacts their functionality but has remained unresolved. Here we quantitatively map the 3' status of cellular RNAs in Escherichia coli during steady-state growth and report a large fraction of molecules (median>60%) that are fragments of canonical full-length mRNAs. The majority of RNA fragments are decay intermediates, whereas nascent RNAs contribute to a smaller fraction. Despite the prevalence of decay intermediates in total cellular RNA, these intermediates are underrepresented in the pool of ribosome-associated transcripts and can thus distort quantifications and differential expression analyses for the abundance of full-length, functional mRNAs. The large heterogeneity within mRNA molecules in vivo highlights the importance in discerning functional transcripts and provides a lens for studying the dynamic life cycle of mRNAs.
细菌的 mRNA 半衰期短，转录后几秒钟到几分钟内即可迅速翻译并降解。不同生命周期阶段的 mRNA 分子的多样性影响其功能，但这一现象尚未得到解决。本研究在大肠杆菌的稳态生长过程中对细胞内 RNA 的 3' 端状态进行了定量分析，并报告了相当大比例（中位数>60%）的分子是典型全长 mRNA 的片段。大多数 RNA 片段是降解中间体，而新生 RNA 则占较小比例。尽管在总细胞 RNA 中降解中间体很普遍，但这些中间体在核糖体相关转录物的池子里代表性不足，因此会扭曲全长、有功能的 mRNA 丰度的定量和差异表达分析。体内 mRNA 分子的高度异质性凸显了区分功能转录本的重要性，并为研究 mRNA 的动态生命周期提供了一个视角。
