A Comparative Study between Spanish and British SARS-CoV-2 Variants

The study of the interaction between the SARS-CoV-2 spike protein and the angiotensin-converting enzyme 2 (ACE2) receptor is key to understanding binding affinity and stability. In the present report, we sought to investigate the differences between two already sequenced genome variants (Spanish and British) of SARS-CoV-2. Methods: In silico model evaluating the homology, identity and similarity in the genome sequence and the structure and alignment of the predictive spike by computational docking methods. Results: The identity results between the Spanish and British variants of the Spike protein were 28.67%. This close correspondence in the results between the Spanish and British SARS-CoV-2 variants shows that they are very similar (99.99%). The alignment obtained results in four deletions. There were 23 nucleotide substitutions also predicted which could affect the functionality of the proteins produced from this sequence. The interaction between the binding receptor domain from the spike protein and the ACE2 receptor produces some of the mutations found and, therefore, the energy of this ligand varies. However, the estimated antigenicity of the British variant is higher than its Spanish counterpart. Conclusions: Our results indicate that minimal mutations could interfere in the infectivity of the virus due to changes in the fitness between host cell recognition and interaction proteins. In particular, the N501Y substitution, situated in the RBD of the spike of the British variant, might be the reason for its extraordinary infective potential.

Polyphenolic Natural Products Active In Silico against SARS-CoV-2 Spike Receptor Binding Domains and Non-Structural Proteins – A Review

: The ongoing Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic has been proven to be more severe than the previous coronavirus outbreaks due to the virus’ high transmissibility. With the emergence of new variants, this global phenomenon took on a more dramatic turn with many countries recently experiencing higher surges of confirmed cases and deaths. On top of this, the inadequacy of effective treatment options for COVID-19 aggravated the problem. As a way to address the unavailability of target-specific viral therapeutics, computational strategies have been employed to hasten and systematize the search. The objective of this review is to provide initial data highlighting the utility of polyphenols as potential prophylaxis or treatment for COVID-19. In particular, presented here are virtually screened polyphenolic compounds which showed potential as either antagonists to viral entry and host cell recognition through binding with various receptor-binding regions of SARS-CoV-2 spike protein or as inhibitors of viral replication and post-translational modifications through binding with essential SARS-CoV-2 non-structural proteins.

Host-cell recognition through GRP78 is enhanced in the new UK variant of SARS-CoV-2, in silico

New SARS-CoV-2 variant VUI 202012/01 started in the UK and currently spreading in Europe and Australia during the last few days. The new variant bears about nine mutations in the spike protein (Δ69-70, Δ145, N501Y, A570D, D614G, P681H, T716I, S982A, and D1118H). The N501Y lies in the receptor-binding domain (RBD) of the spike and interacts with the host-cell receptor ACE2 responsible for viral recognition and entry. We tried to simulate the system of ACE2-SARS-CoV-2 spike RBD in the wildtype and mutated isoform of the RBD (N501Y). Additionally, the GRP78 association with the ACE2-SARS-CoV-2 spike RBD is modeled at the presence of this mutant variant of the viral spike.

Microevolution in the major outer membrane protein OmpA of Acinetobacter baumannii

Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two‐domain proteins with an N‐terminal eight‐stranded β‐barrel domain with four external loops (ELs) interacting with the environment, and a C‐terminal periplasmic domain binding non‐covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus / Acinetobacter baumannii complex (ACB), 946 from A. baumannii , to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii , encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C‐terminal end, and provided evidence for intra‐genic recombination. ompA variants were not randomly distributed across the A . baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A . baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.

COVID-19 Spike-host cell receptor GRP78 binding site prediction

Coronaviruses have been circulating between animals and humans repeatedly. A novel human coronavirus, named COVID-19, has recently emerged in Hubei Province, China. Within the first two months, more than 2200 deaths have been confirmed, and there have been more than 79,000 hospitalized patients, mainly in China. Understanding the virus mode of host cell recognition may help to fight the disease and save lives. The spike protein of coronaviruses is the main driving force for host cell recognition. In this study, the COVID-19 corona viral spike binding site to the cell-surface receptor (Glucose Regulated Protein 78 (GRP78)) is predicted using combined molecular modeling docking and structural bioinformatics. The cyclic peptide Pep42 (CTVALPGGYVRVC) was reported earlier to be the docking platform of GRP78 in cancer cells. The COVID-19 spike protein is modeled using its counterpart, the SARS spike. Sequence and structural alignments show that four regions, in addition to its cyclic nature (the S-S bond), have sequence and physicochemical similarities to the cyclic Pep42. Protein-protein docking was performed to test the four regions of the spike that fit tightly in the GRP78 Substrate Binding Domain β (SBDβ). The docking pose revealed the involvement of the SBDβ of GRP78 and the receptor-binding domain of the coronavirus spike protein in recognition of the host cell receptor. We reveal that the binding is more favorable between regions III (C391-C525) and IV (C480-C488) of the spike protein model and GRP78. Region IV is the main driving force for GRP78 binding with the predicted binding affinity of -9.8 kcal/mol. These nine residues (region IV) of the spike can be used to develop therapeutics specific against COVID-19.

Microevolution in the major outer membrane protein OmpA of Acinetobacter baumannii

Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host cell recognition, biofilm formation, regulation of OM stability, permeability, and antibiotic resistance. OmpA members are two-domain proteins with an N-terminal eight-stranded β-barrel domain with four external loops (ELs) interacting with the environment, and a C-terminal periplasmic domain binding non-covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic, and multilocus sequence analyses from 242 strains of the Acinetobacter calcoaceticus/Acinetobacter baumannii complex (ACB), 222 from A. baumannii, to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) comprising 50 different alleles coding for 29 different proteins. Polymorphisms were concentrated in 5 regions corresponding to the four ELs and the C-terminal end, and provided evidence for different intra-genic recombination events. ompA variants were not randomly distributed across the A. baumannii phylogeny, with the most frequent V1a1 allele almost exclusive to clonal complex 1 (CC1) strains and the second most frequent V2a1 allele found in the majority of CC2 strains. Evidence was found for assortative exchanges of ompA alleles not only between different A. baumannii clonal lineages, but also different ACB species. Within A. baumannii ompA non-synonymous substitutions were concentrated in the ELs regions, but were more abundant in the transmembrane regions between different Acinetobacter species. The overall results have implications for A. baumannii evolution, epidemiology, virulence, and vaccine design.ImportanceAcinetobacter baumannii is an increasing MDR threat in nosocomial settings associated with prolonged hospitalization and concomitantly increased healthcare costs. The main A. baumannii OM protein, OmpA, is a multifaceted two-domain protein implicated in host cell recognition and adhesion, cytotoxicity, biofilm formation, and as a slow porin for antibiotics and small hydrophilic nutrients. A. baumannii OmpA has been proposed as a potential target for anti-virulence drugs and as a vaccine candidate. Given the many interactions of this protein with environmental factors including host defenses, it is certainly subjected to many selective pressures. Here, we analyzed the microevolution of this OM protein in the A. baumannii population to obtain clues on the extent to which selection in the clinical setting has shaped this protein. The results provide relevant information on the main causes driving evolution of this protein, with potential implications in A. baumannii epidemiology, virulence, and vaccine design.

Structure-Based Classification Defines the Discrete Conformational Classes Adopted by the Arenaviral GP1

ABSTRACT The emergence of Old and New World arenaviruses from rodent reservoirs persistently threatens human health. The GP1 subunit of the envelope-displayed arenaviral glycoprotein spike complex (GPC) mediates host cell recognition and is an important determinant of cross-species transmission. Previous structural analyses of Old World arenaviral GP1 glycoproteins, alone and in complex with a cognate GP2 subunit, have revealed that GP1 adopts two distinct conformational states distinguished by differences in the orientations of helical regions of the molecule. Here, through comparative study of the GP1 glycoprotein architectures of Old World Loei River virus and New World Whitewater Arroyo virus, we show that these rearrangements are restricted to Old World arenaviruses and are not induced solely by the pH change that is associated with virus endosomal trafficking. Our structure-based phylogenetic analysis of arenaviral GP1s provides a blueprint for understanding the discrete structural classes adopted by these therapeutically important targets. IMPORTANCE The genetically and geographically diverse group of viruses within the family Arenaviridae includes a number of zoonotic pathogens capable of causing fatal hemorrhagic fever. The multisubunit GPC glycoprotein spike complex displayed on the arenavirus envelope is a key determinant of species tropism and a primary target of the host humoral immune response. Here, we show that the receptor-binding GP1 subcomponent of the GPC spike from Old World but not New World arenaviruses adopts a distinct, pH-independent conformation in the absence of the cognate GP2. Our analysis provides a structure-based approach to understanding the discrete conformational classes sampled by these therapeutically important targets, informing strategies to develop arenaviral glycoprotein immunogens that resemble GPC as presented on the mature virion surface.