RNase E is an essential, multifunctional ribonuclease encoded in E. coli by the rne gene. Structural analysis indicates that the ribonucleolytic activity of this enzyme is conferred by rne-encoded polypeptide chains that (1) dimerize to form a catalytic site at the protein-protein interface, and (2) multimerize further to generate a tetrameric quaternary structure consisting of two dimerized Rne-peptide chains. We identify here a mutation in the Rne protein's catalytic region (E429G), as well as a bacterial cell wall peptidoglycan hydrolase (Amidase C [AmiC]), that selectively affect the specific activity of the RNase E enzyme on long RNA substrates, but not on short synthetic oligonucleotides, by enhancing enzyme multimerization. Unlike the increase in specific activity that accompanies concentration-induced multimerization, enhanced multimerization associated with either the E429G mutation or interaction of the Rne protein with AmiC is independent of the substrate's 5′ terminus phosphorylation state. Our findings reveal a previously unsuspected substrate length-dependent regulatory role for RNase E quaternary structure and identify cis-acting and trans-acting factors that mediate such regulation.

中文翻译：

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四级结构对 RNase E 活性的底物依赖性影响

RNase E 是一种必需的多功能核糖核酸酶，由rne基因在大肠杆菌中编码。结构分析表明，该酶的核糖核酸水解活性是由rne赋予的。-编码的多肽链，(1) 二聚化以在蛋白质-蛋白质界面形成催化位点，和 (2) 进一步多聚化以产生由两条二聚化的 Rne-肽链组成的四聚体四元结构。我们在这里发现了 Rne 蛋白催化区域 (E429G) 以及细菌细胞壁肽聚糖水解酶 (酰胺酶 C [AmiC]) 中的突变，它选择性地影响 RNase E 酶对长 RNA 底物的比活性，但不影响在短合成寡核苷酸上，通过增强酶多聚化。与浓度诱导的多聚化伴随的比活性增加不同，与 E429G 突变或 Rne 蛋白与 AmiC 相互作用相关的多聚化增强与底物的 5' 末端磷酸化状态无关。调节这种调节的顺式作用和反式作用因子。