Understanding Structural Malleability of the SARS-CoV-2 Proteins and their Relation to the Comorbidities
Authors: Sen Sagnik , Dey Ashmita , Bandyopadhyay Sanghamitra , Maulik Ujjwal , Uversky Vladimir 
Published: September 2020

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a causative agent of the coronavirus disease (CoVID-19), is a part of the β-coronaviridae family. In comparison with two other members of this family of coronaviruses infecting humans (SARS-CoV and Middle East Respiratory Syndrome (MERS) CoV), SARS-CoV-2 showed the most severe effects on the entire Earth population causing world-wide CoVID-19 pandemic. SARS-CoV-2 contains five major protein classes, such as four structural proteins (Nucleocapsid (N), Membrane (M), Envelop (E), and Spike Glycoprotein (S)) and Replicase polyproteins (R), which are synthesized as two polyproteins (ORF1a and ORF1ab) that are subsequently processed into 12 nonstructural proteins by three viral proteases. All these proteins share high sequence similarity with their SARS-CoV counterparts. Due to the severity of the current situation, most of the SARS-CoV-2-related research is focused on finding therapeutic solutions and the analysis of comorbidities during infection. However, studies on the peculiarities of the amino acid sequences of viral protein classes and their structure space analysis throughout the evolutionary time-frame are limited. At the same time, due to their structural malleability, viral proteins can be directly or indirectly associated with the dysfunctionality of the host cell proteins, which may lead to comorbidities during the infection and at the post infection stage. To fill these gaps, we conducted the evolutionary sequence-structure analysis of the viral protein classes to evaluate the rate of their evolutionary malleability. We also looked at the intrinsic disorder propensities of these viral proteins and confirmed that although they typically do not have long intrinsically disordered regions (IDRs), all of them have at least some levels of intrinsic disorder. Furthermore, short IDRs found in viral proteins are extremely effective and prioritize the proteins for host cell interactions, which may lead to host cell dysfunction. Next, the associations of viral proteins with the host cell proteins were studied, and a list of diseases which are associated with such host cell proteins was developed. Other than the usual set of diseases, we have identified some maladies, which may happen after the recovery from the infections. Comparison of the expression rates of the host cell proteins during the diseases suggested the existence of two distinct classes. First class includes proteins, which are directly associated with certain sets of diseases, where they have shared similar activities. Second class is related to the cytokine storm-mediated pro-inflammation (already known for its role in acute respiratory distress syndrome, ARDS), and neuroinflammation may trigger some of the neurological malignancies and neurodegenerative and neuropsychiatric diseases. Finally, since the transmembrane serine protease 2 (TMPRSS2), which is one of the leading proteins associated with the viral uptake, is an androgen-mediated protein, our study suggested that males and postmenopausal females can be more susceptible to the SARS-CoV-2 infection.