Maio Nunziata, Terranova Umberto, Li Yan, Bollinger J Martin, Krebs Carsten, Rouault Tracey A
Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
Faculty of Medicine and Health Sciences, The University of Buckingham, Buckingham MK18 1EG & Crewe Campus, Crewe Green Road, Crewe, CW1 5DU, UK.
Nat Commun. 2025 Aug 15;16(1):7585. doi: 10.1038/s41467-025-62832-5.
Coronaviruses rely on a multifunctional replication-transcription complex to ensure genome fidelity and support viral propagation. Within this complex, the nsp14-nsp10 heterodimer possesses 3'-5' exoribonuclease (ExoN) activity, while nsp14 alone functions as an N7-methyltransferase and the nsp16/nsp10 complex completes viral RNA capping via its 2'-O-methyltransferase. Here, we report that nsp14 and nsp10 ligate [FeS] clusters when purified anoxically, in sites previously modeled as zinc centers. Quantum mechanics/molecular mechanics simulations revealed distinct reduction potentials for these iron-sulfur (Fe-S) clusters, and redox titrations demonstrated that changes in oxidation state modulate RNA binding by nsp14 and the nsp10/nsp16 complex. Functionally, Fe-S clusters enhance the methyltransferase activities of nsp14 and nsp10/nsp16, while leaving the ExoN activity unaffected. These findings uncover a redox-regulated role for Fe-S clusters in SARS-CoV-2 RNA processing and suggest that the viral core enzymatic functions may be modulated by the redox state of their Fe-S cofactors.
冠状病毒依靠多功能复制转录复合体来确保基因组保真度并支持病毒繁殖。在这个复合体内，nsp14-nsp10异二聚体具有3'-5'外切核糖核酸酶（ExoN）活性，而单独的nsp14作为N7-甲基转移酶发挥作用，并且nsp16/nsp10复合体通过其2'-O-甲基转移酶完成病毒RNA加帽。在此，我们报告称，当在无氧条件下纯化时，nsp14和nsp10会在先前被模拟为锌中心的位点连接[FeS]簇。量子力学/分子力学模拟揭示了这些铁硫（Fe-S）簇具有不同的还原电位，并且氧化还原滴定表明氧化态的变化会调节nsp14以及nsp10/nsp16复合体与RNA的结合。在功能上，Fe-S簇增强了nsp14和nsp10/nsp16的甲基转移酶活性，而对外切核糖核酸酶活性没有影响。这些发现揭示了Fe-S簇在SARS-CoV-2 RNA加工中具有氧化还原调节作用，并表明病毒核心酶功能可能受其Fe-S辅因子的氧化还原状态调节。
