Published on Fri Apr 16 2021

SARS-CoV-2 proteins bind heme and hemoglobin

De-Simone, S. G., Lechuga, G. C., Souza-Silva, F., Sacramento, C. d. Q., Trugilho, M. R. d. O., Valente, R. H., Napoleao-Pego, P., Dias, S. d. S. G., Fintelman-Rodrigues, N., Temerozzo, J. R., Carels, N., Alves, C. R., Pereira, M. C. d. S., Provance-Jr, D. W., De-Simone, T. M.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome virus 2 (SARS-CoV-2), has led to a global crisis. Despite the number of effective vaccines quickly implemented, the emergence of new variants is a primary concern. The scientific community undertook a rapid response to better study this new virus.

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Abstract

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome virus 2 (SARS-CoV-2), has led to a global crisis that included collapsing healthcare systems and shut-down communities, producing considerable economic burden. Despite the number of effective vaccines quickly implemented, the emergence of new variants is a primary concern. The scientific community undertook a rapid response to better study this new virus. However, critical questions about viral protein-protein interactions and mechanisms of its physiopathology are still unclear. Although severe COVID-19 was associated with hematological dysfunctions, scarce experimental data were produced about iron dysmetabolism and the viral proteins possible interaction with hemoglobin (Hb) chains. This work demonstrates the binding of SARS-CoV-2 proteins to hemin and Hb using a multimethodological approach. In silico analysis indicated binding motifs between a cavity in the viral nucleoprotein and hemoglobins porphyrin coordination region. Different hemin binding capacities of mock and SARS-CoV-2-infected culture extracts were noticed using gel electrophoresis and TMB staining. Hemin-binding proteins were isolated from SARS-CoV-2-infected cells by affinity chromatography and identified by shotgun proteomics, indicating that structural (nucleoprotein, spike, and membrane protein) and non-structural (Nsp3 and Nsp7) viral proteins interact with hemin. In vitro analyses of virus adsorption to host cells and viral replication studies in Vero cells demonstrated inhibitory activities - at different levels - by hemin, protoporphyrin IX (PpIX) Hb. Strikingly, free Hb at 1M suppressed viral replication (99 %), and its interaction with SARS-CoV-2 was localized to the RBD region of the Spike protein. The findings showed clear evidence of new avenues to disrupt viral replication and understand virus physiopathology that warrants further investigation.