The SARS Coronavirus E Protein Interacts with PALS1 and Alters Tight Junction Formation and Epithelial Morphogenesis

Teoh, Kim-Tat; Siu, Yu-Lam; Chan, Wing-Lim; Schlüter, Marc A.; Liu, Chia-Jen; Peiris, J. S. Malik; Bruzzone, Roberto; Margolis, Benjamin; Nal, Béatrice

Here we demonstrate that the small envelope protein E of SARS-CoV interacts with the TJ-associated protein PALS1. The interaction was identified in a yeast-two-hybrid screen (Figure 1A-B). We have verified the E–PALS1 interaction in mammalian epithelial cell by coimmunoprecipitation (Figure 1C) and in vitro by GST-pull down assays (Figure 2B). Moreover, we have demonstrated that E possesses a novel PBM motif at its carboxy-terminal tail, which mediates binding of E to PALS1 PDZ domain (Figure 4, A and B), and that a CT peptide of E but not E (ΔPBM) competes against CRB3 interaction with the PDZ domain of PALS1 in vitro (Figure 4C and data not shown). This latter finding suggests that E-PALS1 association could possibly affect the interaction of PALS1 with CRB3 PBM in epithelial cells, leading to a disruption of TJ and apicobasal polarity.