Inhibition of homologous phosphorolytic ribonucleases by citrate may represent an evolutionarily conserved communicative link between RNA degradation and central metabolism.
Inhibition of homologous phosphorolytic ribonucleases by citrate may represent an evolutionarily conserved communicative link between RNA degradation and central metabolism.
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DOI：
10.1093/nar/gkx114
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发表时间：
2017-05-05
影响因子：
14.9
通讯作者：
Callaghan AJ
中科院分区：
文献类型：
--
作者：
Stone CM;Butt LE;Bufton JC;Lourenco DC;Gowers DM;Pickford AR;Cox PA;Vincent HA;Callaghan AJ
核糖核酸酶在RNA代谢的各个方面都发挥着重要作用，包括协调转录后基因调控，使生物体对内部变化和环境刺激做出反应。然而，作为固有的破坏性酶，它们的活性必须仔细控制。最近的研究例证了核糖核酸酶所采用的调控策略。多核苷酸磷酸化酶(PNPase)是一种磷酸化外核糖核酸酶，其活性受大肠杆菌中Krebs循环代谢物柠檬酸的调节。在这里，我们为柠檬酸介导的核糖核酸酶抑制在生命的所有三个领域的存在提供了证据。在电子计算机分子对接研究中，预测柠檬酸不仅可以与来自大肠杆菌和抗生素链霉菌的细菌PNPase结合，还可以结合来自人类线粒体的PNPase和来自Sulfolobus solfararicus的结构和功能相关的古生菌外体复合体。关键的是，我们的实验表明，柠檬酸还在体外抑制细菌、真核和古生菌PNPase同源物的外切核糖核酸酶活性。此外，生物信息学数据显示，关键的柠檬酸结合基序在广泛的PNPase同源物中保守，表明这种调控机制可能是广泛的。总体而言，我们的数据强调了核糖核酸酶活性和中枢代谢之间的沟通联系，这种联系可能在进化过程中是保守的。
Ribonucleases play essential roles in all aspects of RNA metabolism, including the coordination of post-transcriptional gene regulation that allows organisms to respond to internal changes and environmental stimuli. However, as inherently destructive enzymes, their activity must be carefully controlled. Recent research exemplifies the repertoire of regulatory strategies employed by ribonucleases. The activity of the phosphorolytic exoribonuclease, polynucleotide phosphorylase (PNPase), has previously been shown to be modulated by the Krebs cycle metabolite citrate in Escherichia coli. Here, we provide evidence for the existence of citrate-mediated inhibition of ribonucleases in all three domains of life. In silico molecular docking studies predict that citrate will bind not only to bacterial PNPases from E. coli and Streptomyces antibioticus, but also PNPase from human mitochondria and the structurally and functionally related archaeal exosome complex from Sulfolobus solfataricus. Critically, we show experimentally that citrate also inhibits the exoribonuclease activity of bacterial, eukaryotic and archaeal PNPase homologues in vitro. Furthermore, bioinformatics data, showing key citrate-binding motifs conserved across a broad range of PNPase homologues, suggests that this regulatory mechanism may be widespread. Overall, our data highlight a communicative link between ribonuclease activity and central metabolism that may have been conserved through the course of evolution.