Del Favero Marta, Mazzantini Elisa, Briani Federica, Zangrossi Sandro, Tortora Paolo, Dehò Gianni
Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, 20126 Milan, Italy.
Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, 20133 Milan, Italy.
J Biol Chem. 2008 Oct 10;283(41):27355-27359. doi: 10.1074/jbc.C800113200. Epub 2008 Jul 23.
Polynucleotide phosphorylase (PNPase), an enzyme conserved in bacteria and eukaryotic organelles, processively catalyzes the phosphorolysis of RNA, releasing nucleotide diphosphates, and the reverse polymerization reaction. In Escherichia coli, both reactions are implicated in RNA decay, as addition of either poly(A) or heteropolymeric tails targets RNA to degradation. PNPase may also be associated with the RNA degradosome, a heteromultimeric protein machine that can degrade highly structured RNA. Here, we report that ATP binds to PNPase and allosterically inhibits both its phosphorolytic and polymerization activities. Our data suggest that PNPase-dependent RNA tailing and degradation occur mainly at low ATP concentrations, whereas other enzymes may play a more significant role at high energy charge. These findings connect RNA turnover with the energy charge of the cell and highlight unforeseen metabolic roles of PNPase.
多核苷酸磷酸化酶（PNPase）是一种在细菌和真核细胞器中保守的酶，它持续催化RNA的磷酸解反应，释放出二磷酸核苷酸，并催化反向聚合反应。在大肠杆菌中，这两种反应都与RNA降解有关，因为添加聚（A）或异聚尾巴都会使RNA靶向降解。PNPase也可能与RNA降解体相关，RNA降解体是一种异源多聚体蛋白机器，能够降解高度结构化的RNA。在此，我们报告ATP与PNPase结合并变构抑制其磷酸解和聚合活性。我们的数据表明，依赖PNPase的RNA加尾和降解主要发生在低ATP浓度下，而在高能电荷状态下其他酶可能发挥更重要的作用。这些发现将RNA周转与细胞的能量电荷联系起来，并突出了PNPase不可预见的代谢作用。
