Interactions of Severe Acute Respiratory Syndrome Coronavirus 2 Protein E With Cell Junctions and Polarity PSD-95/Dlg/ZO-1-Containing Proteins

Abstract

The C-terminus of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein E contains a PBM (PDZ-binding motif) targeting PDZ (PSD-95/Dlg/ZO-1) domains, which is identical to the PBM of SARS-CoV. The latter is involved in the pathogenicity of the virus. Recently, we identified 10 human PDZ-containing proteins showing significant interactions with SARS-CoV-2 protein E PBM. We selected several of them involved in cellular junctions and cell polarity (TJP1, PARD3, MLLT4, and LNX2) and MPP5/PALS1 previously shown to interact with SARS-CoV E PBM. Targeting cellular junctions and polarity components is a common strategy by viruses to hijack cell machinery to their advantage. In this study, we showed that these host PDZ domains TJP1, PARD3, MLLT4, LNX2, and MPP5/PALS1 interact in a PBM-dependent manner in vitro and colocalize with the full-length E protein in cellulo, sequestrating the PDZ domains to the Golgi compartment. We solved three crystal structures of complexes between human LNX2, MLLT4, and MPP5 PDZs and SARS-CoV-2 E PBM highlighting its binding preferences for several cellular targets. Finally, we showed different affinities for the PDZ domains with the original SARS-CoV-2 C-terminal sequence containing the PBM and the one of the beta variant that contains a mutation close to the PBM. The acquired mutations in the E protein localized near the PBM might have important effects both on the structure and the ion-channel activity of the E protein and on the host machinery targeted by the variants during the infection.

The Flexible, Extended Coil of the PDZ-Binding Motif of the Three Deadly Human Coronavirus E Proteins Plays a Role in Pathogenicity

“…Moreover, the aspartic acid of the more virulent SARS-CoV-2 (D72) and MERS-CoV (D79) E peptides also shows hydrogen bonding to the PALS1 S281, whereas the SARS-CoV-1 (D76) E peptide does not, while the SARS-CoV-2 E peptide (D72) is the only one to form a hydrogen bond with PALS1 T270. Zhu, et al [114] recently also resolved a SARS-CoV-2 E peptide bound to the PDZ domain of PALS1 (residues 238-336; PDB ID: 7QCS), and our interaction analysis also largely correspond to their experimental findings. Using the number of bonds formed between the E peptide and PALS1 PDZ domain as a measure of stability, this could potentially explain why SARS-CoV-1 was less severe than MERS and COVID-19 and why COVID-19 appears to be more severe than both MERS and SARS diseases were.…”

A short sequence in the tail of SARS-CoV-2 envelope protein controls accessibility of its PDZ Binding Motif to the cytoplasm

“…The E protein expressed at the Golgi apparatus is thought to recruit PDZ domain-containing proteins to this organelle. To test this hypothesis, Hela cells were co-transfected with GFP-ZO-1 full length construct (Figure 4A) and an Alfa tagged E WT(25, 32) encoding plasmid and Golgi localization was quantified using GM130. GFP-ZO-1 full construct exhibits limited co-localization with GM130 (Figure 4B).…”

“…Interestingly, it has been proposed that, by recruiting and sequestrating PALS1 to the Golgi apparatus, SARS-CoV-1 E protein disrupts its trafficking to the tight junction, leading to progressive disassembly of the TJ and leakage between adjacent epithelial cells, ultimately promoting infiltration of the virus into the underlying tissue (24). A screening performed with the last 12 residues of E SARS-CoV-2 proteins has recently identified new PDZ containing proteins interactors such as the TJ protein ZO-1 as well as LNX2, PARD3, and MLLT4 proteins (16, 25). ZO-1 has three PDZ domains but only the second one binds to the PBM motif of the E protein of SARS-CoV-2 (16, 26).…”

Genomic surveillance of SARS-CoV-2 in patients presenting neurological manifestations

“…The two SARS-CoV-2 envelope proteins S and E could play a role in both these mechanisms. Indeed, while the S protein is the main viral tropism determinant [ 10 , 11 ], the E protein is involved in different steps of viral replication and in regulating viral/cell host interactions [ 44 ]. Studies focused on SARS-CoV-1, in particular, have shown that E protein is a virulence factor involved in the activation of various inflammatory pathways [ 45 ].…”