Decoding the structural integrity and multifunctional role of Era protein in the survival of Mycobacterium tuberculosis H37Rv.

Era, a widely known GTP binding protein found in many organisms including prokaryotes and eukaryotes and plays a significant role in many fundamental cellular processes like cell growth, differentiation and signaling. In Mycobacterium tuberculosis (Mtb) H37Rv, Era protein had been proved as a GTPase protein but its structural and functional insights are still lacking. Through comparative analysis, structural modeling, docking and using various bioinformatic tools, a detailed investigation of Era was carried out to deduce the structure, function and residues involved in the activity of the protein. Intriguingly, docking results revealed high binding affinity of Era not only with GTP but also with ATP. Myristoylation modifications and phosphorylations on Era were predicted to possibly aid in regulating Era activity and localization; and also the role of Era in translation regulation was foreseen by showing its association with 16s rRNA. Moreover, point mutation of Era residues revealed the effect of W288G and K19G in highly destabilizing the protein structure and activity. Additionally, Era protein was docked with 25 GTPase/ATPase inhibitors, where, Dynasore inhibitor showed the highest affinity for the protein's GTP binding sites and can be used for further drug trials to inhibit growth of mycobacteria.Communicated by Ramaswamy H. Sarma.

MtEra protein carries five GTP binding motifs (G1, G2, G3, G4 and G5) and one KH domain for RNA binding.Multifunctional role of MtEra predicted in processes like catabolic, metabolic and ribosome biogenesis.Point mutation analysis showed the importance of tryptophan (W) and lysine (K) residues at position 288 and 19 in stability and activity of the protein, respectively.Dynasore inhibitor showed the highest binding energy of −9 kcal/mol for MtEra.

Structural and functional characterization of mycobacterial PhoH2 and identification of potential inhibitor of its enzymatic activity.

Mycobacterium tuberculosis is composed of a cumbersome signaling and protein network which partakes in bacterial survival and augments its pathogenesis. Mycobacterial PhoH2 (Mt-PhoH2) is a signaling element and a predictive phosphate starvation protein that works in an ATP-dependent manner. Here, we elaborated the characterization of Mt-PhoH2 through biophysical, biochemical, and computational methods. In addition to its intrinsic ATPase activity, the biochemical experiments revealed its GTPase activity and both activities are metal ion dependent. Magnesium, manganese, copper, iron, nickel, zinc, cesium, calcium, and lithium were examined for their effect on activity, and the optimum activity was found with 10 mM of Mg2+ ions. The kinetic parameters of 3 µM Mt-PhoH2 were observed as Km 4.873 ± 0.44 µM, Vmax 12.3817 ± 0.084 µM/min/mg, Kcat 0.0075 ± 0.00005 s-1, and Kcat/Km 0.0015 ± 0.000001 µM-1 s-1 with GTP. In the case of GTP as a substrate, a 20% decrease in enzymatic activity and a 50% increase in binding affinity of Mt-PhoH2 were observed. The substrates ADP and GDP inhibit the ATPase and GTPase activity of Mt-PhoH2. CD spectroscopy showed the dominance of alpha helix in the secondary structure of Mt-PhoH2, and this structural pattern was altered upon addition of ATP and GTP. In silico inhibitor screening revealed ML141 and NAV_2729 as two potential inhibitors of the catalytic activity of Mt-PhoH2. Mt-PhoH2 is essential for mycobacterial growth as its knockdown strain showed a decreased growth effect. Overall, the present article emphasizes the factors essential for the proper functioning of Mt-PhoH2 which is a participant in the toxin-antitoxin machinery and may also play an important role in phosphate starvation.

Elucidating the structural and functional prophecy of the Rv2326c gene, an ABC transporter of Mycobacterium tuberculosis H37Rv through computational approach.

Tuberculosis is a fatal disease caused by Mycobacterium tuberculosis. M. tuberculosis becoming drug-resistant day by day, necessitating to know the mechanism behind the drug resistance and how to overcome this deadly malady. Drug resistance and reduced drug bioavailability are caused by a class of transporter proteins called the ATP-binding cassette (ABC) transporters, which pump a range of medicines out of cells at the price of ATP hydrolysis. By using computational approaches, we tried to elaborate the probable function of the Rv2326c gene of M. tuberculosis, perhaps involved in drug resistance mechanism. The presence of the signature motif of ABC transporters (LSGGELQRLALAAAL and LSGGQMRRVVLAGLL) and ATP binding motif (GXXXXGKT and GXXXXGKS) in the protein sequence signifying its importance in the ATP binding and transportation of molecules. Further, this manuscript elaborated about tertiary structure and validation, functional category, localization, phosphorylation site prediction, mutational analysis of conserved motifs. Ligand docking study shows the highest affinity with ATP than GTP justified its function as an ATP binding protein. The Rv2326c protein is present in the inner membrane and working as an ATP binding protein and might be playing a dynamic role in transportation. In this study, we found that Rv2326c protein might be working as an ABC transporter by which the drugs and other molecules are imported or exported into the bacterium. As a result, the current study provides a means to better understand its normal functioning and basic biology, which can help in the development of novel therapeutic targeting approaches for Rv2326c protein.

Development of peptide vaccine candidate using highly antigenic PE-PGRS family proteins to stimulate the host immune response against Mycobacterium tuberculosis H37Rv: an immuno-informatics approach.

Tuberculosis (TB) is a fast spreading; transmissible disease caused by the Mycobacterium tuberculosis (M. tuberculosis). M. tuberculosis has a high death rate in its endemic regions due to a lack of appropriate treatment and preventative measures. We have used a vaccinomics strategy to create an effective multi-epitope vaccine against M. tuberculosis. The antigenic proteins with the highest antigenicity were utilised to predict cytotoxic T-lymphocyte (CTL), helper T-lymphocyte (HTL), and linear B-lymphocyte (LBL) epitopes. CTL and HTL epitopes were covered in 99.97% of the population. Seven epitopes each of CTL, HTL, and LBL were ultimately selected and utilised to develop a multi-epitope vaccine. A vaccine design was developed by combining these epitopes with suitable linkers and LprG adjuvant. The vaccine chimera was revealed to be highly immunogenic, non-allergenic, and non-toxic. To ensure a better expression within the Escherichia coli K12 (E. coli K12) host system, codon adaptation and in silico cloning were accomplished. Following that, various validation studies were conducted, including molecular docking, molecular dynamics simulation, and immunological simulation, all of which indicated that the designed vaccine would be stable in the biological environment and effective against M. tuberculosis infection. The immune simulation revealed higher levels of T-cell and B-cell activity, which corresponded to the actual immune response. Exposure simulations were repeated several times, resulting in increased clonal selection and faster antigen clearance. These results suggest that, if proposed vaccine chimera would test both in-vitro and in-vivo, it could be a viable treatment and preventive strategy for TB.Communicated by Ramaswamy H. Sarma.

A multifactorial assessment of the SRP pathway constituent FtsY as a vital mycobacterial constituent.

The signal recognition particle (SRP) system plays an imperative role in transporting the secretory protein to its intended location. The SRP pathway running in Mycobacterium tuberculosis constitutes FtsY (signal receptor), FfH (SRP), and 4.5S RNA in which signal receptor acts in the GTP-dependent manner. In this study, we are rendering the essential facts of FtsY with respect to mycobacterial growth. The growth study experiment showed that downexpressed FtsY slowed the growth of Mycobacterium smegmatis mc2 155 from the initial lag phase to stationary phase. Previously, we have showed that GTPase activity of FtsY is metal ion dependent and showed the maximum activity with 10 mM magnesium. The effect of Mg2+ and Mn2+ on mycobacterial growth showed that Mg2+ did not affect the growth, whereas higher concentration of Mn2+ decreases the bacterial growth. After searching the inhibitor database, 14 GTPase and ATPase inhibitors, Mac0182344, ML141, ITX3, NAV_2729, Br-GTP, Rhosin_HCl, Mac0182099, CCG_50014, CID_1067700, Mac0174809, Nsc_23766, Berberine, Nexinhib20, and EHT1864, were found to interact with FtsY. Further, ML141 and NAV2729 found to decrease the enzymatic activity of FtsY as well as the mycobacterial growth. Therefore, the conclusive statement of the present study can be stated as that the FtsY plays major role in mycobacterial cell survival and ML141 and NAV2729 can be used to constrain the SRP pathway.

Computational evaluation of anticipated PE_PGRS39 protein involvement in host-pathogen interplay and its integration into vaccine development.

Mycobacterium tuberculosis causes more than 1 million deaths every year, which is higher than any other bacterial pathogen. Its success depends on its interaction with the host and its ability to regulate the host's immune system for its own survival. Mycobacterium tuberculosis H37Rv (Mtb) proteome consists of unique PE_PGRS family proteins, which present a significant role in bacterial pathogenesis over the past years. Earlier evidence suggests that some PE_PGRS proteins display fibronectin-binding activity. In this manuscript, computational characterization of the PE_PGRS39 protein has indicated something peculiar about this protein. Investigation showed that PE_PGRS39 is an extracellular protein that, instead of acting as fibronectin-binding protein, might mimic fibronectin which binds to alpha-5 beta-1 (α5ß1) integrin. PE_PGRS39 protein additionally turned into proven pieces of evidence to have motifs such as DXXG and GGXGXD and PXXP that bind with guanosine triphosphate (GTP), calcium, and host Src homology 3 (SH3) domains, respectively, in conjunction with RGD-integrin binding. These interactions designate the direct role of PE_PGRS39 in bacterial pathogenesis via cell adhesion and signaling. Additionally, the analysis showed that PE_PGRS39 is an antigenic protein and epitope prediction provided functional regions of the protein that trigger a cellular immune response facilitated by T or B cells. Further, an experimental analysis could also open up new avenues for developing novel drugs by targeting signaling motifs or novel vaccines using functional epitopes that could evoke an immune response in the host.

Essential biochemical, biophysical and computational inputs on efficient functioning of Mycobacterium tuberculosis H37Rv FtsY.

Mycobacterium tuberculosis (M. tuberculosis H37Rv) utilizes the signal recognition particle pathway (SRP pathway) system for secretion of various proteins from ribosomes to the extracellular surface which plays an important role in the machinery running inside the bacterium. This system comprises of three major components FtsY, FfH and 4.5S rRNA. This manuscript highlights essential factors responsible for the optimized enzymatic activity of FtsY. Kinetic parameters include Vmax and Km for the hydrolysis of GTP by ftsY which were 20.25±5.16 µM/min/mg and 39.95±7.7 µM respectively. kcat and catalytic efficiency of the reaction were 0.012±0.003 s-1 and 0.00047±0.0001 µM/s-1 respectively. These values were affected upon changing the standard conditions. Cations (Mg2+ and Mn2+) play important role in FtsY enzymatic activity as increasing Mg2+ decrease the activity. Mn2+on the other hand is required at higher concentration around 60 mM for carrying optimum GTPase activity. FtsY is hydrolyzing ATP and GDP as well and GDP acts as an inhibitor of the reaction. MD simulation shows effective binding and stabilization of the FtsY complexed structure with GTP, GDP and ATP. Mutational analysis was done at two important residues of GTP binding motif of FtsY, namely, GXXXXGK (K236) and DXXG (D367) and showed that these mutations significantly decrease FtsY GTPase activity. FtsY is comprised of α helices, but this structural pattern was shown to change with increasing concentrations of GTP and ATP which symbolize that these ligands cause significant conformational change by variating the secondary structure to transduce signals required by downstream effectors. This binding favors the functional stabilization of FtsY by destabilization of α-helix integrity. Revealing the hidden aspects of the functioning of FtsY might be an essential part for the understanding of the SRP pathway which is one of the important contributors of M. tuberculosis virulence.

A comprehensive review of COVID-19 in India: A frequent catch of the information.

The arrival of novel health crisis by a novel member of coronavirus group named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by World Health Organization took the whole world in global emergency by affecting 206 countries. The virus infects 206 countries with 86,839,226 confirmed cases, 61,565,949 recoveries, and 1,876,243 deaths as on January 6, 2021. Evidence pointed out the fact that virus might first originated in bats in China and it took only 2 months to spread over almost every country of the world. SARS-CoV-2 belongs to beta coronavirus and is enveloped, positive sense, and single-stranded RNA virus. The treatment would be difficult as SARS-CoV-2 is an RNA virus and thus the mutation rate is higher in comparison with the DNA viruses. The virus infection also leads to generation of effective protective immune response of tumor necrosis factor, interleukin (IL)-1ß, IL-6, IL-8, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and so on that may help in virus elimination. The speed of the global spread of the current pandemic is of major concern and it has created a significant threat to economic and human health across the world. In India, the infection spreads with an infection and fatality rates of the disease are 1.7% and 2.8%, respectively. By this review, we want to emphasize the actual situation and major factors associated with COVID-19 pandemic, its significance, destructions, important findings, treatments, and preventive measures taken by all nations to provide better cure without having much loss.

Comprehensive analysis of GTP cyclohydrolase I activity in Mycobacterium tuberculosis H37 Rv via in silico studies.

GTP cyclohydrolase I enzyme (GTPCH-I) is a rate limiting enzyme in the biosynthesis pathway of tetrahydrobiopterin (BH4) and tetrahydrofolate (THF) compounds; latter being are an essential compounds involved in many biological functions. This enzyme has been evaluated structurally and functionally in many organisms to understand its putative role in cell processes, kinetics, regulations, drug targeting in infectious diseases, pain sensitivity in humans, and so on. In Mycobacterium tuberculosis (a human pathogen causing tuberculosis), this GTPCH-I activity has been predicted to be present in Rv3609c gene (folE) of H37 Rv strain, which till date has not been studied in detail. In order to understand in depth, the structure and function of folE protein in M. tuberculosis H37 Rv, in silico study was designed by using many different bioinformatics tools. Comparative and structural analysis predicts that Rv3609c gene is similar to folE protein ortholog of Listeria monocytogenes (cause food born disease), and uses zinc ion as a cofactor for its catalysis. Result shows that mutation of folE protein at 52th residue from tyrosine to glycine or variation in pH and temperature can lead to high destability in protein structure. Studies here have also predicted about the functional regions and interacting partners involved with folE protein. This study has provided clues to carry out experimentally the analysis of folE protein in mycobacteria and if found suitable will be used for drug targeting.

Revelation of point mutations effect in Mycobacterium tuberculosis MfpA protein that involved in mycobacterial DNA supercoiling and fluoroquinolone resistance.

MfpA protein encoded by Mycobacterium tuberculosis (Mtb) and stands for Mycobacterium fluoroquinolone resistance protein A. This protein provides Mtb intrinsic resistant property from fluoroquinolone antibiotics by inhibiting DNA gyrase that are known to be the primary target of fluoroquinolone drugs. DNA gyrases are important for bacterial chromosomal genesis as they are majorly involved in DNA replication, transcription, bacterial stress response to several external stimulus. Therefore, in Mtb it forms an essential integrity and also a desirable target for drug development approaches. This article implies on determining the essential facts about mfpA including its interaction study, epitope prediction, modelling and validation and most importantly it deals with the mutation. Mutational analysis was carried out on the basis of sequential information and there were several mutations that cause a large decrease in stability of the protein. Total 24 mutations were shortlisted based on ΔΔG value W154G, F54G, L84G, F9G, W4G, F74G, F64G, F49G, L104G, L94G, L124G, F29G, L39G, L59G, W60G, L114G, W154G, W154S, L19G, L144G, L129G, F34G, W154D, W154A and W4S. Separate mutation on DXXG GTPase motif was examined to check any effect on protein stability and we found that D33A, D98A, D128A, G36A, G101A, G131A, D33G, D98G, D128G, G36W, G101W, G131W, D33K, D98K, D128K decreases protein stability the most. Further stress dependent analysis on selected residues showed that lower temperature and pH destabilizes the protein. The reason behind this increase in protein destability was drastic decrease and disruption of interatomic interactions in mutant MfpA. This analysis provides essential information about the residues that are important for MfpA stability and also enlightens protein vulnerability after mutation. This article is protected by copyright. All rights reserved.

Calcium ATPase signaling: A must include mechanism in the Radar of therapeutics development against Tuberculosis.

An article presented by Peterson and Verkhratsky in 2016 explore the linkage of calcium and ATP for a themed issue of "Evolution brings Ca2+  and ATP together to control life and death". The article impacted due to several findings of their cooperative functioning such as the formulation of ATP necessitates a small concentration of cytosolic Ca2+ , and therefore leads these two molecules together. The low cytosolic Ca2+ concentration is a primary advantage of its function like a universal secondary messenger. The present article also explores the essential facts about Ca2+ -ATP signaling in response to tuberculosis (TB). TB is still a major causal mortality of an important fraction of worldwide population and therefore we require an urgent regimen for its treatment. The new strategies that cover all forms of the disease MDR, XDR and TDR are necessity to overcome the disease pattern and its outcomes. Ionophores and channels mediated transportation of Ca2+ that leads to elevation of intra cellular Ca2+ concentration provide an important clue to divert the focus towards this signaling mechanism. P2×7 pathway is an enormous Ca2+ signaling pathway that incorporated Ca2+ influx and Potassium efflux upon activation by ATP molecule. After this activation, immune components like 1L-12 and IL-6 release and generate a protective response against pathogen. This review highlights importance of togetherness of Ca2+ and ATP signaling with new and more emphasize view of Ca2+ regulation. This article is protected by copyright. All rights reserved.

Analysis of predicted amino acid biosynthesis in Rv3344c in Mycobacterium tuberculosis H37 Rv using bioinformatics tools.

According to World Health Organization (WHO) report, Mycobacterium tuberculosis H37 Rv (M. tuberculosis) affects one-third population of the world. Emergence of effective treatment/research against this disease is need of the hour. Therefore, we present some important aspects of Rv3344c, which is a PE_PGRS protein. Evidence shows that PE_PGRS proteins show fibronectin binding activity. This protein has affinity for calcium and also shows motifs of GTP-binding protein. It also shows the presence of sites for ribose-5-phosphate binding and motifs of aspartate-beta-semialdehyde dehydrogenase, both of which are involved in amino acid biosynthesis. Thus, this protein might be targeted to block the amino acid biosynthesis in M. tuberculosis. This article takes into consideration some important aspects of Rv3344c protein as its function is still unknown. This study includes retrieval of protein sequence database, multiple sequence alignment, protein-protein interaction, epitope prediction, localization, function prediction, phosphorylation site prediction, model building and its validation, ligand-binding prediction along with mutational analysis. Hence, this study might be an important step in the development of new drugs and treatment of tuberculosis.

Adhesion molecules facilitate host-pathogen interaction & mediate Mycobacterium tuberculosis pathogenesis.

Most of the microorganisms display adhesion molecules on their surface which help them to bind and interact with the host cell during infection. Adhesion molecules help mycobacteria to colonize and invade immune system of the host, and also trigger immune response explicated by the host against the infection. Hence, understanding the signalling pathways illustrated by these molecules to enhance our knowledge on mycobacterial survival and persistence inside the host cell is required. Hence, this review was focussed on the role of adhesion molecules and their receptor molecules. The various mechanisms adopted by adhesion molecules to bind with the specific receptors on the host cell and their role in invasion and persistence of mycobacterium inside the host cell are explained.

Interrelation of Ca2+ and PE_PGRS proteins during Mycobacterium tuberculosis pathogenesis.

In today's era tuberculosis is a major threat to human population. The lethality of this disease is caused by very efficiently thrived bacteria Mycobacterium tuberculosis (M. tuberculosis). Ca2+ plays crucial role in maintenance of cellular homeostasis. Bacilli survival in human alveolar macrophages majorly depends on disruption in Ca2+ signaling. Bacilli sustainability in phagosome lies in the interruption of phagolysosomal fusion, which is possible because of low intracellular Ca2+ concentration. Bacilli contain various Ca2+ binding proteins which help in regulation of Ca2+ signaling for its own benefit. For the survival of pathogen, it requires alteration in normal Ca2+ concentration in healthy cell. In this review we aim to find the various Ca2+ binding domains which are present in several Ca2+ binding proteins of M. tuberculosis and variety of roles played by Ca2+ to survive bacilli within host cell. This manuscript emphasizes the Ca2+ binding domains present in PE_PGRS group of gene family and their functionality in M. tuberculosis survival and pathogenesis.

Structural Prediction and Mutational Analysis of Rv3906c Gene of Mycobacterium tuberculosis H37Rv to Determine Its Essentiality in Survival.

The emergence of tuberculosis is at the peak; therefore to station it at its lower level we hereby try bioinformatics approach against Mycobacterium tuberculosis [M. tuberculosis] pathogenesis. Rv3906c is a conserved hypothetical gene of M. tuberculosis and contains many GTP binding protein motif DXXG which demonstrate that this gene might be processed in a GTP binding or in GTP hydrolyzing manner. This gene shows interaction with its adjacent genes as well as pcnA which is a polymerase and localized in the extracellular region and found to be a soluble protein. Rv3906c has binding pockets for calcium atom at various positions which prove that calcium might have some role during the process of this gene. GTP binding protein motif DXXG is present in various positions and calcium binds at this site with a C-score of 0.25. Mutational analysis on this motif shows the large decrease of stability after mutation of aspartate residue with glycine. Stress conditions like pH and temperature also change stability of the protein. A decrease in stability at this position might play a role in inhibition of survival of the pathogen. These computational studies of this gene might be a successful step towards drug development against tuberculosis.

Triacylglycerol: nourishing molecule in endurance of Mycobacterium tuberculosis.

The ability of Mycobacterium tuberculosis (M. tuberculosis) to accumulate lipid-rich molecules as an energy source obtained from host cell debris remains interesting. Additionally, the potential of M. tuberculosis to survive under different stress conditions leading to its dormant state in pathogenesis remains elusive. The exact mechanism by which these lipid bodies generated in M. tuberculosis infection and utilized by bacilli inside infected macrophage for its survival is still not understood. In this, during bacillary infection, many metabolic pathways are involved that influence the survival of M. tuberculosis for their own support. However, the exact energy source derived from infecting host cells remain elusive. Therefore, this study highlights several alternative energy sources in the form of triacylglycerol (TAG) and fatty acids, i.e. oleic acids accumulation, which are essential in dormancy-like state under M. tuberculosis infection. The prominent stage in tuberculosis (TB) infection is re-establishment of M. tuberculosis under stress conditions and deployment of a confined strategy to utilize these biomolecules for its persistence survival. So, growing in our understanding of these pathways will help us in accelerating therapies, which could reduce TB prevalence world widely.

A Novel Approach in Treatment of Tuberculosis by Targeting Drugs to Infected Macrophages Using Biodegradable Nanoparticles.

Mycobacterium tuberculosis, the causative agent of tuberculosis is now causing death of more than 10 million people. Because of the development of drug-resistant TB, drug delivery to the infected site through nanoparticle had been studied for long time. Nanoparticles indicate different sorts of association with the natural particles of the body. Nanoparticles can be used as controlled or specific drug delivery system. It can be through temporal controlled or can be distribution controlled. Glucose polymer-based nanoparticles might play an important role as drug delivery system in case of targeted drug delivery in the infected site of the body or in infected macrophages, as they are biodegradable so there should not be any side effects of these particles in the body and also they show very slow immune response. CD4, Beta 1, TGFb-1, IL-2, IL-13 SEC14L1, GUSB, BPI, and CCR7 are major biomarkers secreted after infection of this bacterium by the macrophages which can be used for targeted drug delivery in infected macrophages. As these markers can be used for delivery of drugs at destined position, they can be very beneficial in reducing toxicities of antituberculer drugs to the other uninfected sites and in operating only the infected macrophages.

Potential of Ca2+ in Mycobacterium tuberculosis H37Rv Pathogenesis and Survival.

The host-pathogen interaction and involvement of calcium (Ca2+) signaling in tuberculosis infection is crucial and plays a significant role in pathogenesis. Ca2+ is known as a ubiquitous second messenger that could control multiple processes and is included in cellular activities like division, motility, stress response, and signaling. However, Ca2+ is thought to be a regulative molecule in terms of TB infection but its binding relation with proteins/substrates molecules which are influenced with Ca2+ concentrations in host-pathogen interaction requires attention. So, in this review, our primary goal is to focus on some Ca2+ substrates/proteins and their imperative involvement in pathogenesis, which is unclear. We have discussed several Ca2+-binding substrate and protein that affect intracellular mechanism of infected host cell. The major involvement of these proteins/substrates including calmodulin (CaM), calpain, annexin, surfactant protein A (SP-A), surfactant protein D (SP-D), calprotectin (MRP8/14), and PE_PGRS family protein are considered to be significant; however, their detailed understanding in mycobacterium infection is limited. In this aspect, this study will help in adding up our understanding in TB biology and additionally in the development of new therapeutic approach to reduce TB pandemic worldwide.

Biochemical characterization of PE_PGRS61 family protein of Mycobacterium tuberculosis H37Rv reveals the binding ability to fibronectin.

OBJECTIVES: The periodic binding of protein expressed by Mycobacterium tuberculosis H37Rv with the host cell receptor molecules i.e. fibronectin (Fn) is gaining significance because of its adhesive properties. The genome sequencing of M. tuberculosis H37Rv revealed that the proline-glutamic (PE) proteins contain polymorphic GC-rich repetitive sequences (PGRS) which have clinical importance in pathogenesis events when the host encounters M. tuberculosis H37Rv. The functional parts of PE_PGRS family proteins, have not been extensively studied in tuberculosis biology. MATERIALS AND METHODS: Fibronectin (10 ng and 20 ng) were used for FnBP assay and its enzymatic activities were observed by using various protein concentrations. RESULTS: Therefore, in the present work, we cloned, expressed, purified and identified a novel PE_PGRS61 (Rv3653) family protein in M. tuberculosis H37Rv. Our experiment, observation suggested that at particular concentrations of 10 ng and 20 ng of Fn exhibits optimum binding to the purified Fibronectin Binding Protein (FnBP), a PE_PGRS61 family protein at 0.20 µg and 0.25 µg concentrations, respectively. Moreover, for better understanding the computational analysis, the B-cell and T-cell epitopes prediction prospect some amino acid propensity scales with hydrophilicity and antigenic variation index at their respective locations. CONCLUSION: Thus, the current findings provide an opportunity to illuminate the functions of PE_PGRS61 family protein. So, in this point of view, it could be useful to develop a novel therapeutic approach or diagnostic pipeline through targeting these fibronectin binding protein (FnBP) expressing genes.

Fibronectin binding protein and Ca2+ play an access key role to mediate pathogenesis in Mycobacterium tuberculosis: An overview.

The anomalous distribution of adhesive proteins throughout on the cell surface of the Mycobacterium tuberculosis H37 Rv and their contribution in cell surface adhesion and host-pathogen interaction remain elusive. The completion of M. tuberculosis H37 Rv genome sequence analysis gives some interesting information about polymorphic GC-rich repetitive sequence (PGRS) subfamily of M. tuberculosis that encodes fibronectin binding proteins (FnBP), which have been extensively studied, but the function in the pathogenesis of most of these proteins remains unknown and unclear. This review addresses the M. tuberculosis entry mechanism in the host cell. In particular, an effort has been made to focus on several aspects, (a) association of FnBP encodes by PE_PGRS protein family of M. tuberculosis during host-pathogen interactions. (b) Effect of calcium ions in and outside of the host cell is overriding to maintenance of calcium trafficking in phagocytosis. Furthermore, FnBP may be a potential source of antigenic variation that participating in evoking immune response. M. tuberculosis entry mechanism does not have a major influence alone, involvement of calcium ions, perhaps shed light on host-pathogen interaction relationship, and could open up new avenues for development of novel drug by targeting M. tuberculosis FnBP and blockade of selective adhesions could be useful for therapeutics.