Docking, thermodynamics and molecular dynamics (MD) studies of a non-canonical protease inhibitor, MP-4, from Mucuna pruriens

Anti-Peri-implantitis Bacteria's Ability of Robusta Green Coffee Bean (Coffea Canephora) Ethanol Extract: An In Silico and In Vitro Study

OBJECTIVE

 This study was aimed to investigate RGCBE extract as antioxidant and anti-peri-implantitis bacteria through in vitro study and its potential as antioxidant, antibacterial, anti-inflammatory, antibone resorption, and proosteogenic through in silico study.

MATERIALS

AND METHODS:  Absorption, distribution, metabolism, excretion and toxicity prediction, molecular docking simulation, and visualization of chlorogenic acid (CGA) and coumaric acid (CA) as anti-inflammatory, antioxidant, and antibacterial were investigated in silico. Inhibition zone by diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of RGCBE extract against Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn), and Prevotella intermedia (Pi) were done.

STATISTICAL ANALYSIS

the analysis of variance (ANOVA) difference test, and the post-hoc Tukey's Honest Significant Different (HSD) with a different significance value of p<0.05 RESULTS:  GCA and CA compounds are good drug molecules and it has low toxicity. Chlorogenic acid have higher binding activity than coumaric acid to tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB, receptor activation NF-κB (RANK) and its ligand (RANKL), interleukin (IL)-6, IL-10, runt related transcription factor (RUNX2), receptor activator nuclear Kappa beta Ligand-osteoprotegrin osteocalcin (RANKL-OPG), osteocalcin, nuclear factor associated T-cell 1 (NFATc1), tartate resistant acid phosphatase (TRAP), peptidoglycan, flagellin, dectin, Hsp70, and Hsp10 protein. RGCB ethanol extract has high antioxidant ability and it has MIC, MBC, and inhibit the growth of Aa, Pg, Fn, and Pi at 50% concentration with significantly different (p=0.0001 and<0.05).

CONCLUSION

 RGCB ethanol extract has high antioxidant ability and 50% RGCB ethanol extract may act as strong anti-peri-implantitis bacteria in vitro. In addition, CGA in RGCB potential as antioxidant, antibacterial, anti-inflammatory, antibone resorption, and proosteogenic in silico.

Canonical or noncanonical? Structural plasticity of serine protease-binding loops in Kunitz-STI protease inhibitors

The Kunitz-Soybean Trypsin Inhibitor (Kunitz-STI) family is a large family of proteins with most of its members being protease inhibitors. The versatility of the inhibitory profile and the structural plasticity of these proteins, make this family a promising scaffold for designing new multifunctional proteins. Historically, Kunitz-STI inhibitors have been classified as canonical serine protease inhibitors, but new inhibitors with novel inhibition mechanisms have been described in recent years. Different inhibition mechanisms could be the result of different evolutionary pathways. In the present work, we performed a structural analysis of all the crystallographic structures available for Kunitz-STI inhibitors to characterize serine protease-binding loop structural features and locations. Our study suggests a relationship between the conformation of serine protease-binding loops and the inhibition mechanism, their location in the β-trefoil fold, and the plant source of the inhibitors. The classical canonical inhibitors of this family are restricted to plants from the Fabales order and bind their targets via the β4-β5 loop, whereas serine protease-binding loops in inhibitors from other plants lie mainly in the β5-β6 and β9-β10 loops. In addition, we found that the β5-β6 loop is used to inhibit two different families of serine proteases through a steric blockade inhibition mechanism. This work will help to change the general perception that all Kunitz-STI inhibitors are canonical inhibitors and proteins with protease-binding loops adopting noncanonical conformations are exceptions. Additionally, our results will help in the identification of protease-binding loops in uncharacterized or newly discovered inhibitors, and in the design of multifunctional proteins.

Seed Storage Protein, Functional Diversity and Association with Allergy

Plants are essential for humans as they serve as a source of food, fuel, medicine, oils, and more. The major elements that are utilized for our needs exist in storage organs, such as seeds. These seeds are rich in proteins, show a broad spectrum of physiological roles, and are classified based on their sequence, structure, and conserved motifs. With the improvements to our knowledge of the basic sequence and our structural understanding, we have acquired better insights into seed proteins and their role. However, we still lack a systematic analysis towards understanding the functional diversity associated within each family and their associations with allergy. This review puts together the information about seed proteins, their classification, and diverse functional roles along with their associations with allergy.

A study of deregulated MMR pathways and anticancer potential of curcuma derivatives using computational approach

Plant derived products have steadily gained momentum in treatment of cancer over the past decades. Curcuma and its derivatives, in particular, have diverse medicinal properties including anticancer potential with proven safety as supported by numerous in vivo and in vitro studies. A defective Mis-Match Repair (MMR) is implicated in solid tumors but its role in haematologic malignancies is not keenly studied and the current literature suggests that it is limited. Nonetheless, there are multiple pathways interjecting the mismatch repair proteins in haematologic cancers that may have a direct or indirect implication in progression of the disease. Here, through computational analysis, we target proteins that are involved in rewiring of multiple signaling cascades via altered expression in cancer using various curcuma derivatives (Curcuma longa L. and Curcuma caesia Roxb.) which in turn, profoundly controls MMR protein function. These biomolecules were screened to identify their efficacy on selected targets (in blood-related cancers); aberrations of which adversely impacted mismatch repair machinery. The study revealed that of the 536 compounds screened, six of them may have the potential to regulate the expression of identified targets and thus revive the MMR function preventing genomic instability. These results reveal that there may be potential plant derived biomolecules that may have anticancer properties against the tumors driven by deregulated MMR-pathways.

Carbon nanotubes for rapid capturing of SARS-COV-2 virus: revealing a mechanistic aspect of binding based on computational studies

We investigate the binding interactions of synthesized multi-walled carbon nanotubes (MWCNTs) with SARS-CoV-2 virus. Two essential components of the SARS-CoV-2 structure i.e.6LU7 (main protease of SARS-CoV-2) and 6LZG (spike receptor-binding domain complexed with its receptor ACE2) were used for computational studies. MWCNTs of different morphologies (zigzag, armchair and chiral) were synthesized through a thermal chemical vapour deposition process as a function of pyrolysis temperature. A direct correlation between radius to volume ratio of the synthesized MWCNTs and the binding energies for all three (zigzag, armchair and chiral) conformations were observed in our computational studies. Our result suggests that MWCNTs interact with the active sites of the main protease along with the host angiotensin-converting enzyme2 (ACE2) receptors. Furthermore, it is also observed that MWCNTs have significant binding affinities towards SARS-CoV-2. However, the highest free binding energy of -87.09 kcal mol-1 with 6LZG were shown by the armchair MWCNTs with SARS-CoV-2 through the simulated molecular dynamic trajectories, which could alter the SARS-CoV-2 structure with higher accuracy. The radial distribution function also confirms the density variation as a function of distance from a reference particle of MWCNTs for the study of interparticle interactions of the MWCNT and SARS-CoV-2. Due to these interesting attributes, such MWCNTs could find potential application in personal protective equipment (PPE) and diagnostic kits.

S. mansoni SmKI-1 Kunitz-domain: Leucine point mutation at P1 site generates enhanced neutrophil elastase inhibitory activity

The Schistosoma mansoni SmKI-1 protein is composed of two domains: a Kunitz-type serine protease inhibitor motif (KD) and a C-terminus domain with no similarity outside the genera. Our previous work has demonstrated that KD plays an essential role in neutrophil elastase (NE) binding blockage, in neutrophil influx and as a potential anti-inflammatory molecule. In order to enhance NE blocking capacity, we analyzed the KD sequence from a structure-function point of view and designed specific point mutations in order to enhance NE affinity. We substituted the P1 site residue at the reactive site for a leucine (termed RL-KD), given its central role for KD's inhibition to NE. We have also substituted a glutamic acid that strongly interacts with the P1 residue for an alanine, to help KD to be buried on NE S1 site (termed EA-KD). KD and the mutant proteins were evaluated in silico by molecular docking to human NE, expressed in Escherichia coli and tested towards its NE inhibitory activity. Both mutated proteins presented enhanced NE inhibitory activity in vitro and RL-KD presented the best performance. We further tested RL-KD in vivo in an experimental model of monosodium urate (MSU)-induced acute arthritis. RL-KD showed reduced numbers of total cells and neutrophils in the mouse knee cavity when compared to KD. Nevertheless, both RL-KD and KD reduced mice hypernociception in a similar fashion. In summary, our results demonstrated that both mutated proteins showed enhanced NE inhibitory activity in vitro. However, RL-KD had a prominent effect in diminishing inflammatory parameters in vivo.

Synthesis of exfoliated multilayer graphene and its putative interactions with SARS-CoV-2 virus investigated through computational studies

Our work investigates the interaction of synthesized graphene with the SARS-CoV-2 virus using molecular docking and molecular dynamics (MD) simulation method. The layer dependent inhibitory effect of graphene nanosheets on spike receptor-binding domain of 6LZG, complexed with host receptor i.e. angiotensin-converting enzyme 2 (ACE2) of SARS-CoV-2 was investigated through computational study. Graphene sample was synthesized using mechanical exfoliation with shear stress and its mechanism of inhibition towards the SARS-CoV-2 virus was explored by molecular docking and molecular dynamics (MD) simulation method. The thermodynamics study for the free binding energy of graphene towards the SARS-CoV-2 virus was analyzed. The binding energy of graphene towards the virus increased with an increasing number of layers. It shows the highest affinity of -17.5 Kcal/mol in molecular docking while ΔG_binding is in the order of -28.01 ± 0.04 5 Kcal/mol for the seven-layers structure. The increase in carbon layers is associated with an increasing number of edge sp³ -type carbon, providing greater curvature, further increase the surface reactivity responsible for high binding efficiency. The MD simulation data reveals the high inhibition efficiency of the synthesized graphene towards SARS-CoV-2 virus which would help to design future in-vitro studies. The graphene system could find potential applications in personal protective equipment and diagnostic kits.Communicated by Ramaswamy H. Sarma.

Adaptive selection in the evolution of programmed cell death-1 and its ligands in vertebrates

Programmed cell death-1 (PD-1) and its ligands, particularly PD-L1 and PD-L2, are the most important proteins responsible for signaling T-cell inhibition and arbitrating immune homeostasis and tolerance mechanisms. However, the adaptive evolution of these genes is poorly understood. In this study, we aligned protein-coding genes from vertebrate species to evaluate positive selection constraints and evolution in the PD1, PD-L1 and PD-L2 genes conserved across up to 166 vertebrate species, with an average of 55 species per gene. We determined that although the positive selection was obvious, an average of 5.3% of codons underwent positive selection in the three genes across vertebrate lineages, and increased positive selection pressure was detected in both the Ig-like domains and transmembrane domains of the proteins. Moreover, the PD1, PD-L1 and PD-L2 genes were highly expressed in almost all tissues of the selected species indicating a distinct expression pattern in different tissues among most species. Our study reveals that adaptive selection plays a key role in the evolution of PD1 and its ligands in the majority of vertebrate species, which is in agreement with the contribution of these residues to the mechanisms of pathogen identification and coevolution in the complexity and novelties of vertebrate immune systems.

The structure of MP-4 from Mucuna pruriens at 2.22 Å resolution

The structure of the MP-4 protein was previously determined at a resolution of 2.8 Å. Owing to the unavailability of gene-sequence information at the time, the side-chain assignment was carried out on the basis of a partial sequence available through Edman degradation, sequence homology to orthologs and electron density. The structure of MP-4 has now been determined at a higher resolution (2.22 Å) in another space group and all of the structural inferences that were presented in the previous report of the structure were validated. In addition, the present data allowed an improved assignment of side chains and enabled further analysis of the MP-4 structure, and the accuracy of the assignment was confirmed by the recently available gene sequence. The study reinforces the traditional concept that conservative interpretations of relatively low-resolution structures remain correct even with the availability of high-resolution data.