Probing the mechanical properties of ORF3a protein, a transmembrane channel of SARS-CoV-2 virus: Molecular dynamics study

SARS-CoV-2-encoded accessory protein ORF3a was found to be a conserved coronavirus protein that shows crucial roles in apoptosis in cells as well as in virus release and replications. To complete the knowledge and identify the unknown of this protein, further comprehensive research is needed to clarify the leading role of ORF3a in the functioning of the coronavirus. One of the efficient approaches to determining the functionality of this protein is to investigate the mechanical properties and study its structural dynamics in the presence of physical stimuli. Herein, performing all-atom steered molecular dynamics (SMD) simulations, the mechanical properties of the force-bearing components of the ORF3a channel are calculated in different physiological conditions. As variations occurring in ORF3a may lead to alteration in protein structure and function, the G49V mutation was also simulated to clarify the relationship between the mechanical properties and chemical stability of the protein by comparing the behavior of the wild-type and mutant Orf3a. From a physiological conditions point of view, it was observed that in the solvated system, the presence of water molecules reduces Young's modulus of TM1 by ∼30 %. Our results also show that by substitution of Gly49 with valine, Young's modulus of the whole helix increases from 1.61 ± 0.20 to 2.08 ± 0.15 GPa, which is consistent with the calculated difference in free energy of wild-type and mutant helices. In addition to finding a way to fight against Covid-19 disease, understanding the mechanical behavior of these biological nanochannels can lead to the development of the potential applications of the ORF3a protein channel, such as tunable nanovalves in smart drug delivery systems, nanofilters in the new generation of desalination systems, and promising applications in DNA sequencing.