Coronavirus PDZ-binding-motifs and virus virulence

Trabajo presentado en el Keystone Symposia on Molecular and Cellular Biology. Positive-Strand RNA Viruses, celebrado en Killarney, Kerry (Irlanda), del 9 al 13 de junio de 2019Coronaviruses (CoV) are pathogens responsible for a wide range of existing and emerging diseases. CoVs of genera, and encode proteins that have a PDZ-binding motif (PBM), which may bind over 400 cellular proteins containing PDZ domains, making them relevant for the control of cell function. Two highly pathogenic human CoVs have been identified to date: SARS-CoV and MERS-CoV. In this communication, the relevance of these CoV PBMs in virulence has been studied. First, recombinant SARS-CoV and MERS-CoV variants missing each of these PBMs were generated. Their pathogenicity was analyzed in mice showing that the PBMs of the E proteins of these two viruses were virulence factors, in contrast to the PBMs of proteins 3a and 5 of these viruses, respectively. To study the mechanisms of virulence induced by these PBMs, the cellular PDZ domains interacting with them were identified using a specific yeast-two-hybrid platform restricted to the 256 known human PDZ. More than 20 cellular proteins were identified, and four (syntenin, PTPN13, DLG1 and LNX2) were selected for further study as they interacted with SARS-CoV and MERS-CoV E protein PBMs and are involved in the pro-inflammatory response. It was shown that syntenin activated p38MAPK which induced an exacerbated proinflammatory response leading to virus pathogenesis. In view of the published data, the four cellular PDZ proteins may act by promoting the activation of p38MAPK indicating that these four pathways converged to produce the same effect. In fact, inhibition of p38MAPK lead to the survival of at least 80% of the infected mice, confirming the relevance of this signaling pathway. Preliminary data showed that syntenin PDZ had significantly higher avidity for SARS-CoV and MERS-CoV E protein PBMs than for the corresponding motifs of proteins 3a and 5 of these viruses, suggesting a potential correlation between the avidity of cellular PDZs for viral PBMs, and virus virulence. These results strongly suggest that CoVs PBMs are potential targets for antiviral therapy.This work was supported by grants of the Science Department (Spain), European Commission and NIH (USA)