The non-structural protein Nsp10 of mouse hepatitis virus binds zinc ions and nucleic acids

The non-structural protein Nsp10 of coronaviruses is a small cleavage product of the viral replicase polyprotein that has been implicated in RNA synthesis. Nsp10 of mouse hepatitis virus (MHV) displays an apparent molecular mass of 13–16 kDa in reducing SDS–PAGE and analytical gel filtration, while dynamic light scattering suggests the existence of oligomeric forms. Atomic absorption spectroscopy reveals two metal ions per Nsp10 monomer, with a preference for Zn2+ over Fe2+/3+ and Co2+. These are probably bound by two Zn-finger-like motifs. Moreover, MHV Nsp10 interacts with tRNA, single-stranded RNA, double-stranded DNA and, to a lesser extent, single-stranded DNA as shown by gel-shift experiments. The Kd for tRNA is 2.1 ± 0.2 μM.