Régnier P, Arraiano C M
Institut de Biologie Physico-Chimique and Université Paris 7, Paris, France.
Bioessays. 2000 Mar;22(3):235-44. doi: 10.1002/(SICI)1521-1878(200003)22:3<235::AID-BIES5>3.0.CO;2-2.
The amount of a messenger RNA available for protein synthesis depends on the efficiency of its transcription and stability. The mechanisms of degradation that determine the stability of mRNAs in bacteria have been investigated extensively during the last decade and have begun to be better understood. Several endo- and exoribonucleases involved in the mRNA metabolism have been characterized as well as structural features of mRNA which account for its stability have been determined. The most important recent developments have been the discovery that the degradosome-a multiprotein complex containing an endoribonuclease (RNase E), an exoribonuclease (polynucleotide phosphorylase), and a DEAD box helicase (RhlB)-has a central role in mRNA degradation and that oligo(A) tails synthesized by poly(A) polymerase facilitate the degradation of mRNAs and RNA fragments. Moreover, the phosphorylation status and the base pairing of 5' extremities, together with 3' secondary structures of transcriptional terminators, contribute to the stability of primary transcripts. Degradation of mRNAs can follow several independent pathways. Interestingly, poly(A) tails and multienzyme complexes also control the stability and the degradation of eukaryotic mRNAs. These discoveries have led to the development of refined models of mRNA degradation.
可用于蛋白质合成的信使核糖核酸（mRNA）的量取决于其转录效率和稳定性。在过去十年中，人们对决定细菌中mRNA稳定性的降解机制进行了广泛研究，并开始有了更深入的了解。已对几种参与mRNA代谢的内切核糖核酸酶和外切核糖核酸酶进行了表征，同时也确定了影响其稳定性的mRNA结构特征。最近最重要的进展是发现降解体——一种包含内切核糖核酸酶（核糖核酸酶E）、外切核糖核酸酶（多核苷酸磷酸化酶）和DEAD盒解旋酶（RhlB）的多蛋白复合物——在mRNA降解中起核心作用，以及由多聚腺苷酸聚合酶合成的寡聚（A）尾巴促进了mRNA和RNA片段的降解。此外，5'末端的磷酸化状态和碱基配对，以及转录终止子的3'二级结构，都有助于初级转录本的稳定性。mRNA的降解可以遵循几种独立的途径。有趣的是，多聚（A）尾巴和多酶复合物也控制真核生物mRNA的稳定性和降解。这些发现推动了更精细的mRNA降解模型的发展。
