Gerlier, D. | bioRxiv Science

bioRxiv2020

Activation of cGAS/STING pathway upon paramyxovirus infection

During inflammatory diseases, cancer and infection, the cGAS/STING pathway is known to recognize foreign or self-DNA in the cytosol and activate an innate immune response. Here, we report that negative-strand RNA paramyxoviruses, Nipah virus (NiV) and Measles virus (MeV), can also trigger the cGAS/STING axis. While mice deficient for MyD88, TRIF and MAVS still moderately control NiV infection when compared to WT mice, additional STING deficiency resulted in 100% lethality, suggesting synergistic roles of these pathways in host protection. Moreover, deletion of cGAS or STING resulted in decreased type-I interferon production with enhanced paramyxoviral infection in both human and murine cells. Finally, the phosphorylation and ubiquitination of STING, observed during viral infections, confirmed the activation of cGAS/STING pathway by NiV and MeV. Our data suggest that cGAS/STING activation is critical in controlling paramyxovirus infection, and possibly represent attractive targets to develop countermeasures against severe disease induced by these pathogens.

immunology↗

bioRxiv2020

Predicting substitutions to modulate disorder and stability in coiled-coils

Coiled-coils are described as stable structural motifs, where two or more helices wind around each other. However, coiled-coils are associated with local mobility and intrinsic disorder. Intrinsically disordered regions (IDRs) in proteins are characterized by lack of stable secondary and tertiary structure under physiological conditions in vitro. They are increasingly recognized as important for protein function. However, characterizing their behaviour in solution and determining precisely the extent of disorder of a protein region remains challenging, both experimentally and computationally. In this work, we propose a computational framework to quantify the extent of disorder within a coiled-coil in solution and to help design substitutions modulating such disorder. Our method relies on the analysis of conformational ensembles generated by relatively short all-atom Molecular Dynamics (MD) simulations. We apply it to the phosphoprotein multimerisation domains (PMD) of Measles virus (MeV) and Nipah virus (NiV), both forming tetrameric left-handed coiled-coils. We show that our method can help quantify the extent of disorder of the C-terminus region of MeV and NiV PMDs, without requiring the input MD trajectory to actually sample the unfolded states of these regions. Moreover, this study provided a conceptual framework for the rational design of substitutions aimed at modulating the stability of the coiled-coils. By assessing the impact of four substitutions known to destabilize coiled-coils, we derive a set of rules to control MeV PMD structural stability and cohesiveness. We therefore design two contrasting substitutions, one increasing the stability of the tetramer and the other increasing its flexibility. Consequently, our method can be considered as a platform to reason about how to design substitutions aimed at regulating flexibility and stability.

bioinformatics↗