Identification of motif-based interactions between SARS-CoV-2 protein domains and human peptide ligands pinpoint antiviral targets.

The infection and replication cycle of all viruses depend on interactions between viral and host proteins. Each of these protein-protein interactions is therefore a potential drug target. These host-virus interactions often involve a disordered protein region on one side of the interface and a folded protein domain on the other. Here, we used proteomic peptide phage display (ProP-PD) to identify peptides from the intrinsically disordered regions of the human proteome that bind to folded protein domains encoded by the SARS-CoV-2 genome. Eleven folded domains of SARS-CoV-2 proteins were found to bind peptides from human proteins. Of 281 high/medium confidence peptides, 23 interactions involving eight SARS-CoV-2 protein domains were tested by fluorescence polarization, and binding was observed with affinities spanning the whole micromolar range. The key specificity determinants were established for six of these domains, two based on ProP-PD and four by alanine scanning SPOT arrays. Finally, two cell-penetrating peptides, targeting Nsp9 and Nsp16, respectively, were shown to function as inhibitors of viral replication. Our findings demonstrate how high-throughput peptide binding screens simultaneously provide information on potential host-virus interactions and identify ligands with antiviral properties.

Large scale discovery of coronavirus-host factor protein interaction motifs reveals SARS-CoV-2 specific mechanisms and vulnerabilities

Viral proteins make extensive use of short peptide interaction motifs to hijack cellular host factors. However, current methods do not identify this important class of protein-protein interactions. Uncovering peptide mediated interactions provides both a molecular understanding of viral interactions with their host and the foundation for developing novel antiviral reagents. Here we describe a scalable viral peptide discovery approach covering 229 RNA viruses that provides high resolution information on direct virus-host interactions. We identify 269 peptide-based interactions for 18 coronaviruses including a specific interaction between the human G3BP1/2 proteins and an {Phi}xFG peptide motif in the SARS-CoV-2 nucleocapsid (N) protein. This interaction supports viral replication and through its {Phi}xFG motif N rewires the G3BP1/2 interactome to disrupt stress granules. A peptide-based inhibitor disrupting the G3BP1/2-N interaction blocks SARS-CoV-2 infection showing that our results can be directly translated into novel specific antiviral reagents.