matfax
commented
4 years ago Summary
In this study from 2005, Zhinan Chen et al. analyzed the protein-protein interaction of CD147, cyclophilin A (CyPA), and different proteins of SARS-CoV. Using SPR, they noted that there is no direct binding of SARS-CoV proteins (i.e., S, M, E, and N proteins) with CD147. CypA, however, was shown to bind to the N protein of SARS-CoV only. An extended SPR analysis further showed a concentration-dependent correlation to the binding affinity of the N protein. Co-IP analysis confirmed the interaction of CypA with the N protein. Moreover, Co-IP showed an interaction of CypA with CD147. EM pictures showed that CypA clustered at the surface of subcellular SARS-CoV viruses. Furthermore, they showed CD147 clustered on the cell surface and on the membrane of the cell and endoplasmic reticulum. FCM determined comparable rates of CD147 expression and AP-9 binding in a HEK293 cell line (i.e. 98.56% and 98.15% respectively). Respectively, double-stained immunofluorescence pictures confirmed that CD147 and AP-9 used the same binding sites. EM also showed the colocalization of CD147 and AP-9. AP-9 could block CD147 binding and induce recovery of infected cells.
Comment
No figures are included to verify the results regarding S, M, and E proteins. Their Co-IP experiments separately show an interaction of CypA with CD147 and CypA with the SARS-CoV N protein but not of all three parallelly. At the time of publishing, no method is known for coronaviruses in which CypA can directly bind to the N protein since it is no surface protein. Yet, their EM pictures showed an accumulation of CypA at the surface of the virus. In the discussion, the authors ascribe this phenomenon to the maturation phase in that the N protein is accessible for CypA and that CypA is then relocated from the N protein to the surface of the virus because such a mechanism has been shown for HIV-1. This deduction seems to be far fetched as a conclusive claim because they haven’t verified it by an experiment. No data shows how these CypA-positive matured viruses propagate or that it is indeed the maturation phase in which CypA accumulates and moves to the virus surface. The significant result of this study is that CypA can bind to SARS-CoV N protein and that CypA can accumulate at the surface of subcellular matured SARS-CoV viruses. It is also important to notice that there is no direct interaction of SARS-CoV surface proteins with CD147 but CypA might enable an interaction.
I have an undergraduate science degree. Please read it critically.
Title: Function of HAb18G/CD147 in Invasion of Host Cells by Severe Acute Respiratory Syndrome Coronavirus
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Link: https://doi.org/10.1086/427811
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Citation: doi:10.1086/427811
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