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

Conversely, at the same time point, MDCKII eGFP-PALS1, HA-E (wt) cells had not yet polarized (Figure 7B). Indeed, confocal microscopy analysis revealed that the majority of cells was flat, with round cells locally occasionally lying on top of the monolayer. The subcellular localization of eGFP-PALS1 was significantly affected. Although the protein was still found at the cell–cell contacts, it was present at lower levels. GP135 did not specifically distribute to the apical surfaces but localized diffusely to the cell cytoplasm (Figure 7B, panel a). ZO-1 was found at the cell–cell junctions, preferentially at apical regions of the cells where it only partially colocalized with eGFP-PALS1 (Figure 7B, panel b, white arrows). The HA-E (wt) protein was expressed in a perinuclear compartment, suggestive of localization to the ERGIC/Golgi compartment (Figure 7B). Of note, a partial colocalization of eGFP-PALS1 and HA-E (wt) was observed in some cells (Figure 7B, panel b, white arrowheads), suggesting a partial retention of PALS1 by E in intracellular compartments.