An iron–sulfur cluster in the zinc-binding domain of the SARS-CoV-2 helicase modulates its RNA-binding and -unwinding activities

Nunziata Maio, Md Kausar Raza, Yan Li, De Liang Zhang, J. Martin Bollinger, Carsten Krebs, Tracey A. Rouault

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, uses an RNA-dependent RNA polymerase along with several accessory factors to replicate its genome and transcribe its genes. Nonstructural protein (nsp) 13 is a helicase required for viral replication. Here, we found that nsp13 ligates iron, in addition to zinc, when purified anoxically. Using inductively coupled plasma mass spectrometry, UV-visible absorption, EPR, and Mössbauer spectroscopies, we characterized nsp13 as an iron–sulfur (Fe–S) protein that ligates an Fe4S4 cluster in the treble-clef metal-binding site of its zinc-binding domain. The Fe–S cluster in nsp13 modulates both its binding to the template RNA and its unwinding activity. Exposure of the protein to the stable nitroxide TEMPOL oxidizes and degrades the cluster and drastically diminishes unwinding activity. Thus, optimal function of nsp13 depends on a labile Fe–S cluster that is potentially targetable for COVID-19 treatment.

Original languageEnglish (US)
Article numbere2303860120
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number33
StatePublished - 2023

All Science Journal Classification (ASJC) codes

  • General

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