Arenaviridae exoribonuclease presents genomic RNA edition capacity

Elsie Yekwa; Chutima Aphibanthammakit; Xavier Carnec; Bruno Coutard; Caroline Picard; Bruno Canard; Sylvain Baize; François Ferron

The MOPV NP-exo exhibits a metal-dependent 3'-5' ExoN activity. The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/541698 doi: bioRxiv preprint exo MOPV is able to cleave this stable RNA hairpin (DG=-14.7 kcal/mole) predominantly down to a 18-mer product. After removing the 1 st 4 nucleotides, degradation stops at the loop region. A similar experiment in the presence of Mn 2+ allows further degradation into the loop, whereas ExoN is inactive in the presence of either Zn 2+ or Ca 2+ . The laddering degradation pattern visualized on the gel, together with radio-label quantification indicate that it acts in the 3'-5' direction (S2B Fig). Visual examination of degradation kinetics shows, a band-product accumulation prior to G nucleotides, indicating that the latter are slower to remove than Cs. We also tested the ExoN activity of the ExoN domain of NP-LCMV (NP-exo LCMV) (Fig 1A) on the same RNA substrate. Both proteins cleave the RNA following a similar degradation pattern and comparable kinetics (S2B Fig and S3 Table) . The two ExoNs exhibit their highest activity in the presence of Mn 2+ , followed by Mg 2+ and they are inactive in the presence of either Ca 2+ or Zn 2+ or EDTA (Fig 1A ) . These results show that the nature of the ions is altering the ExoN activity and its associated pattern of degradation can be greatly modulated by the nature of the metal ion co-factor.