Abstract
Angiotensin-converting enzyme 2 (ACE2) is a main receptor for SARS-CoV-2 entry to the host cell. Indeed, the first step in viral entry is the binding of the viral trimeric spike (S) protein to ACE2. Abundantly present in human epithelial cells of many organs, ACE2 is also expressed in the human brain. ACE2 is a type I membrane protein with an extracellular N-terminal peptidase domain and a C-terminal collectrin-like domain that ends with a single transmembrane helix and an intracellular 44-residue segment. This C-terminal segment contains a PDZ-binding motif (PBM) targeting protein-interacting domains called PSD-95/Dlg/ZO-1 (PDZ). Here, we identified the human PDZ specificity profile of the ACE2 PBM using the high-throughput holdup assay and measuring the binding intensities of the PBM of ACE2 against the full human PDZome. We discovered 14 human PDZ binders of ACE2 showing significant binding with dissociation constants’ values ranging from 3 to 81 μM. NHERF, SHANK, and SNX27 proteins found in this study are involved in protein trafficking. The PDZ/PBM interactions with ACE2 could play a role in ACE2 internalization and recycling that could be of benefit for the virus entry. Interestingly, most of the ACE2 partners we identified are expressed in neuronal cells, such as SHANK and MAST families, and modifications of the interactions between ACE2 and these neuronal proteins may be involved in the neurological symptoms of COVID-19.
Highlights
Three human coronaviruses have appeared since the early 2000s and caused epidemics: SARS-CoV (2003), MERS-CoV (2012), and SARS-CoV-2 (2019)
Angiotensin-converting enzyme 2 (ACE2) is involved in blood pressure regulation and cleaves a range of substrates involved in different physiological processes
ACE2 receptors, proteases such TMPRSS2, and furin are important for viral entry into host cells for coronaviruses such as SARS-CoV-2
Summary
Three human coronaviruses have appeared since the early 2000s and caused epidemics: SARS-CoV (2003), MERS-CoV (2012), and SARS-CoV-2 (2019). The entry step begins with the attachment of the viral particle to the cell surface This is based on the interaction between the spicules on the surface of the viral particle (spike protein S of SARS-CoV-2) and the glycoprotein angiotensin-converting enzyme 2 (ACE2) which acts as an entry receptor [1]. Cathepsin L is ubiquitously expressed in mammalian cells and cleaves the S2 and activates the fusion between viral and endosomal membranes, leading to the release of the viral RNA into the host cell cytoplasm [5] where the virus replicates [6]. SARS-CoV-2 can infect human cells expressing ACE2. The ACE2 PDZ-binding motif binds notably to neuronal proteins, SHANK and MAST1/MAST2 proteins, that could participate in the neurological alterations in patients infected by SARS-CoV-2
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