Enzymes Involved in Posttranscriptional RNA Metabolism in Gram-Negative Bacteria.
Enzymes Involved in Posttranscriptional RNA Metabolism in Gram-Negative Bacteria.
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DOI：
10.1128/microbiolspec.rwr-0011-2017
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发表时间：
2018-04
影响因子：
3.7
通讯作者：
Kushner SR
中科院分区：
文献类型：
--
作者：
Mohanty BK;Kushner SR
革兰氏阴性细菌中的基因表达在多个层面上受到调节，包括转录起始、RNA 加工、RNA/RNA 相互作用、mRNA 衰减以及涉及改变翻译效率的酶的翻译控制。在本章中，我们讨论通过 RNA 加工和降解控制转录、翻译和 RNA 稳定性的各种酶。 RNA 加工对于生成功能性 RNA 至关重要，而降解有助于控制每个转录本的稳态水平。例如，所有前 tRNA 均在其 5' 和 3' 末端转录有额外的核苷酸，随后加工产生可氨酰化的成熟 tRNA。类似地，作为 30S 多顺反子转录物一部分转录的 rRNA 成熟为单独的 16S、23S 和 5S rRNA。 mRNA 的衰变通过控制每个转录物的稳态水平在基因调控中发挥着关键作用，这对于维持适当的蛋白质水平至关重要。此外，翻译和非翻译 RNA 的降解可回收核苷酸以促进新 RNA 的合成。为了进行所有这些反应，革兰氏阴性细菌使用大量核酸内切酶、核酸外切酶、RNA解旋酶和聚腺苷酸聚合酶以及调节特定核糖核酸酶催化活性的蛋白质。在某些应激条件下，另一组专门的核酸内切酶可促进细胞的适应和生存能力。许多酶，例如 RNase E、RNase III、多核苷酸磷酸化酶、RNase R 和 Poly(A) 聚合酶 I 参与多种 RNA 加工和降解途径。
Gene expression in Gram-negative bacteria is regulated at many levels, including transcription initiation, RNA processing, RNA/RNA interactions, mRNA decay, and translational controls involving enzymes that alter translational efficiency. In this chapter we discuss the various enzymes that control transcription, translation and RNA stability through RNA processing and degradation. RNA processing is essential to generate functional RNAs, while degradation helps control the steady-state level of each individual transcript. For example, all the pre-tRNAs are transcribed with extra nucleotides at both their 5′ and 3′ termini, which are subsequently processed to produce mature tRNAs that can be aminoacylated. Similarly, rRNAs that are transcribed as part of a 30S polycistronic transcript, are matured to individual 16S, 23S and 5S rRNAs. Decay of mRNAs plays a key role in gene regulation through controlling the steady-state level of each transcript, which is essential for maintaining appropriate protein levels. In addition, degradation of both translated and non-translated RNAs recycles nucleotides to facilitate new RNA synthesis. To carry out all these reactions Gram-negative bacteria employ a large number of endonucleases, exonucleases, RNA helicases, and poly(A) polymerase as well as proteins that regulate the catalytic activity of particular ribonucleases. Under certain stress conditions an additional group of specialized endonucleases facilitate the cell’s ability to adapt and survive. Many of the enzymes, such as RNase E, RNase III, polynucleotide phosphorylase, RNase R, and poly(A) polymerase I participate in multiple RNA processing and decay pathways.