PBITV3 : A robust and comprehensive tool for screening pathogenic proteomes for drug targets and prioritizing vaccine candidates.

Rise of life-threatening superbugs, pandemics and epidemics warrants the need for cost-effective and novel pharmacological interventions. Availability of publicly available proteomes of pathogens supports development of high-throughput discovery platforms to prioritize potential drug-targets and develop testable hypothesis for pharmacological screening. The pipeline builder for identification of target (PBIT) was developed in 2016 and updated in 2021, with the purpose of accelerating the search for drug-targets by integration of methods like comparative and subtractive genomics, essentiality/virulence and druggability analysis. Since then, it has been used for identification of drugs and vaccine targets, safety profiling of multiepitope vaccines and mRNA vaccine construction against a broad-spectrum of pathogens. This tool has now been updated with functionalities related to systems biology and immuno-informatics and validated by analyzing 48 putative antigens of Mycobacterium tuberculosis documented in literature. PBITv3 available as both online and offline tools will enhance drug discovery against emerging drug-resistant infectious agents. PBITv3 can be freely accessed at http://pbit.bicnirrh.res.in/.

Mammalian cysteine-rich secretory proteins interact with plasma membrane Ca2+ exporter PMCA4b.

BACKGROUND: Mammalian cysteine-rich secretory proteins (CRISPs) are predominantly expressed in the male reproductive tract. Knockout mice lacking two or more CRISPs show defects in sperm transport, sperm-egg interaction and Ca2+ homeostasis. CRISPs play redundant and specific roles via their binding partners. To understand this, a comprehensive analysis of CRISP interactome needs to be undertaken. OBJECTIVES: This study aimed to analyse CRISP4 binding partners on the plasma membrane of rat caudal spermatozoa. MATERIALS AND METHODS: Total proteins from rat caudal spermatozoa were subjected to immunoprecipitation using anti-CRISP4 antibody followed by liquid chromatography-mass spectrophotometry analysis. Plasma membrane localised proteins were shortlisted, and a key target was validated by co-immunoprecipitation and co-localisation. Co-transfection followed by co-immunoprecipitation was carried out for studying the interaction of full-length as well as deletion mutants of CRISPs with human plasma membrane calcium ATPase, isoform b (hPMCA4b). Calcium assays were performed using Fura-2-AM. The cholesterol binding ability of different CRISPs was evaluated in silico. RESULTS: The membrane-specific interactome of rat CRISP4 (rCRISP4) from caudal spermatozoa revealed PMCA4b as a novel binding partner, and their interaction was validated in rat spermatozoa. Human CRISP1 (hCRISP1) and hCRISP3 also interacted with PMCA4b via the N-terminal domain. Interestingly, hCRISP1 and rCRISP4 delayed PMCA4b-mediated calcium extrusion but hCRISP3 did not. In silico analysis demonstrated that hCRISP1 and rCRISP4 have higher binding affinity towards cholesterol than hCRISP3. The secretion profile of different CRISPs also showed that the ratio of secreted to cell-associated proteins was highest for hCRISP3. CONCLUSION: Our study identifies PMCA4b as a target of multiple mammalian CRISPs and unravels a new role of CRISPs in regulating calcium homeostasis. Differences in the interaction of different CRISPs with cholesterol may regulate their enrichment in the lipid rafts and redistribution in the membrane post-capacitation, thereby affecting their interaction with PMCA4b.

Genomic and computational analysis of four novel variants of MPL gene in Congenital Amegakaryocytic Thrombocytopenia.

Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, genetic, autosomal recessive disorder characterized by severe thrombocytopenia, due to inefficient bone marrow megakaryopoiesis eventually leading to aplasia. Majority of the cases are due to homozygous or compound heterozygous mutations in MPL gene encoding for thrombopoietin (THPO) receptor protein. CAMT can be diagnosed at early phase of life, with major complication of transfusion dependency and hematopoietic transplantation as only curative treatment. We have investigated the sequence variations in MPL gene of 7 bone marrow failure (BMF) subjects, who presented with clinically diverse phenotypes, through next generation sequencing (NGS). Plasma THPO levels were estimated using ELISA. Insilico sequence and structure-based analyses were performed to understand the structural and functional implications of mutations, identified through NGS. We studied 7 CAMT subjects suspected of BMF, who presented with severe thrombocytopenia followed by pancytopenia, bleeding manifestation and physical anomalies. The plasma THPO levels were significantly elevated (p<0.05) in all the cases. Molecular analysis by NGS identified 9 genomic mutations in MPL gene. These included 7 non-synonymous substitution, 1 nonsense substitution and 1 in-del mutations, of which 4 are novel mutations. Insilico analysis predicted damaging effects on THPO-R and its reduced affinity for THPO for all the identified mutations. CAMT is a rare disorder with diverse clinical phenotypes and diagnosis is challenging. The elevated plasma THPO levels should be considered for the primary diagnosis and prognosis of the disease. However, molecular analysis of MPL gene is important for the diagnosis and management of the disease through genetic counselling. Though the cytokines, THPO-R agonist are used for the treatment of CAMT, HSCT is the only curative therapy.

FSHR activation through small molecule modulators: Mechanistic insights from MD simulations.

Follicle-stimulating hormone receptor (FSHR) is a glycoprotein hormone receptor that plays a vital role in reproduction, cancer progression and osteoporosis. Owing to its therapeutic importance, several small molecule modulators have been identified by researchers through high throughput studies that usually include virtual screening of chemical libraries followed by in vitro validation through radio-ligand binding assays, cAMP accumulation and luciferase-based luminescence assays. The binding site of these modulators and structural changes that accompany modulator binding remains elusive. Here, we address these aspects through molecular docking and MD simulations on well-studied FSHR modulators and comparing the domain motions between agonist/FSH bound and antagonist bound FSHR structures. It was observed that agonist and antagonist modulators bind to the same site, but interact with distinct residues in transmembrane domain(TMD). FSHR(TMD) residues Ile522, Ala595, Ile602 and Val604 were found to interact only with agonist. Notably, these residues are conserved in the close homolog luteinizing hormone/choriogonadotropin receptor (LHCGR) and participate in interaction with its agonist Org43553. We observed distinctly prominent domain motions and conformational changes in TM helices 3, 4 and 6 for agonist bound FSHR structure. These structural changes have also been reported for LHCGR, and few GPCR members suggesting an important and well conserved mechanism of GPHR activation that could be exploited for design of novel modulators.

CAMPR4: a database of natural and synthetic antimicrobial peptides.

There has been an exponential increase in the design of synthetic antimicrobial peptides (AMPs) for its use as novel antibiotics. Synthetic AMPs are substantially enriched in residues with physicochemical properties known to be critical for antimicrobial activity; such as positive charge, hydrophobicity, and higher alpha helical propensity. The current prediction algorithms for AMPs have been developed using AMP sequences from natural sources and hence do not perform well for synthetic peptides. In this version of CAMP database, along with updating sequence information of AMPs, we have created separate prediction algorithms for natural and synthetic AMPs. CAMPR4 holds 24243 AMP sequences, 933 structures, 2143 patents and 263 AMP family signatures. In addition to the data on sequences, source organisms, target organisms, minimum inhibitory and hemolytic concentrations, CAMPR4 provides information on N and C terminal modifications and presence of unusual amino acids, as applicable. The database is integrated with tools for AMP prediction and rational design (natural and synthetic AMPs), sequence (BLAST and clustal omega), structure (VAST) and family analysis (PRATT, ScanProsite, CAMPSign). The data along with the algorithms of CAMPR4 will aid to enhance AMP research. CAMPR4 is accessible at http://camp.bicnirrh.res.in/.

Expanding the therapeutic options for Candida infections using novel inhibitors of secreted aspartyl proteases.

For widening the therapeutic options for Candida management, the druggability of Candida proteome was systematically investigated using an innovative pipeline of high-throughput data mining algorithms, followed by in vitro validation of the observations. Through this exercise, HIV-1 protease was found to share structural similarity with secreted aspartyl protease-3 (SAP3), a virulence protein of Candida. Using the molecular fingerprint of HIV-1 protease inhibitor GRL-09510, we performed virtual screening of peptidomimetic library followed by high-precision docking and MD simulations for discovery of SAP inhibitors. Wet-lab validation of the four shortlisted peptidomimetics revealed that two molecules, when used in combination with fluconazole, could significantly reduce the dosage of fluconazole required for 50% inhibition of Candida albicans. The SAP inhibitory activity of these peptidomimetics was confirmed through SAP assays and found to be on par with pepstatin A, a known peptidomimetic inhibitor of aspartyl proteases.

N-Linked Glycosylation in Chinese Hamster Ovary Cells Is Critical for Insulin-like Growth Factor 1 Signaling.

Cell surface proteins carrying N-glycans play important roles in inter- and intracellular processes including cell adhesion, development, and cellular recognition. Dysregulation of the glycosylation machinery has been implicated in various diseases, and investigation of global differential cell surface proteome effects due to the loss of N-glycosylation will provide comprehensive insights into their pathogenesis. Cell surface proteins isolated from Parent Pro-5 CHO cells (W5 cells), two CHO mutants with loss of N-glycosylation function derived from Pro-5 CHO (Lec1 and Lec4 cells), were subjected to proteome analysis via high-resolution LCMS. We identified 44 and 43 differentially expressed membrane proteins in Lec1 and Lec4 cells, respectively, as compared to W5 cells. The defective N-glycosylation mutants showed increased abundance of integrin subunits in Lec1 and Lec4 cells at the cell surface. We also found significantly reduced levels of IGF-1R (Insulin like growth factor-1 receptor); a receptor tyrosine kinase; and the GTPase activating protein IQGAP1 (IQ motif-containing GTPase activating protein), a highly conserved cytoplasmic scaffold protein) in Lec1 and Lec4 cells. In silico docking studies showed that the IQ domain of IQGAP1 interacts with the kinase domain of IGF-1R. The integrin signaling and insulin growth factor receptor signaling were also enriched according to GSEA analysis and pathway analysis of differentially expressed proteins. Significant reductions of phosphorylation of ERK1 and ERK2 in Lec1 and Lec4 cells were observed upon IGF-1R ligand (IGF-1 LR3) stimulation. IGF-1 LR3, known as Long arginine3-IGF-1, is a synthetic protein and lengthened analog of insulin-like growth factor 1. The work suggests a novel mechanism for the activation of IGF-1 dependent ERK signaling in CHO cells, wherein IQGAP1 plausibly functions as an IGF-1R-associated scaffold protein. Appropriate glycosylation by the enzymes MGAT1 and MGAT5 is thus essential for processing of cell surface receptor IGF-1R, a potential binding partner in IQGAP1 and ERK signaling, the integral components of the IGF pathway.

Human surfactant protein D facilitates SARS-CoV-2 pseudotype binding and entry in DC-SIGN expressing cells, and downregulates spike protein induced inflammation.

Lung surfactant protein D (SP-D) and Dendritic cell-specific intercellular adhesion molecules-3 grabbing non-integrin (DC-SIGN) are pathogen recognising C-type lectin receptors. SP-D has a crucial immune function in detecting and clearing pulmonary pathogens; DC-SIGN is involved in facilitating dendritic cell interaction with naïve T cells to mount an anti-viral immune response. SP-D and DC-SIGN have been shown to interact with various viruses, including SARS-CoV-2, an enveloped RNA virus that causes COVID-19. A recombinant fragment of human SP-D (rfhSP-D) comprising of α-helical neck region, carbohydrate recognition domain, and eight N-terminal Gly-X-Y repeats has been shown to bind SARS-CoV-2 Spike protein and inhibit SARS-CoV-2 replication by preventing viral entry in Vero cells and HEK293T cells expressing ACE2. DC-SIGN has also been shown to act as a cell surface receptor for SARS-CoV-2 independent of ACE2. Since rfhSP-D is known to interact with SARS-CoV-2 Spike protein and DC-SIGN, this study was aimed at investigating the potential of rfhSP-D in modulating SARS-CoV-2 infection. Coincubation of rfhSP-D with Spike protein improved the Spike Protein: DC-SIGN interaction. Molecular dynamic studies revealed that rfhSP-D stabilised the interaction between DC-SIGN and Spike protein. Cell binding analysis with DC-SIGN expressing HEK 293T and THP- 1 cells and rfhSP-D treated SARS-CoV-2 Spike pseudotypes confirmed the increased binding. Furthermore, infection assays using the pseudotypes revealed their increased uptake by DC-SIGN expressing cells. The immunomodulatory effect of rfhSP-D on the DC-SIGN: Spike protein interaction on DC-SIGN expressing epithelial and macrophage-like cell lines was also assessed by measuring the mRNA expression of cytokines and chemokines. RT-qPCR analysis showed that rfhSP-D treatment downregulated the mRNA expression levels of pro-inflammatory cytokines and chemokines such as TNF-α, IFN-α, IL-1ß, IL- 6, IL-8, and RANTES (as well as NF-κB) in DC-SIGN expressing cells challenged by Spike protein. Furthermore, rfhSP-D treatment was found to downregulate the mRNA levels of MHC class II in DC expressing THP-1 when compared to the untreated controls. We conclude that rfhSP-D helps stabilise the interaction between SARS- CoV-2 Spike protein and DC-SIGN and increases viral uptake by macrophages via DC-SIGN, suggesting an additional role for rfhSP-D in SARS-CoV-2 infection.

Mapping of FSHR agonists and antagonists binding sites to identify potential peptidomimetic modulators.

Owing to the critical role of follicle stimulating hormone receptor (FSHR) signaling in human reproduction, FSHR has been widely explored for development of fertility regulators. Using high-throughput screening approaches, several low molecular weight (LMW) compounds that can modulate FSHR activity have been identified. However, the information about the binding sites of these molecules on FSHR is not known. In the present study, we extracted the structural and functional information of 161 experimentally validated LMW FSHR modulators available in PubMed records. The potential FSHR binding sites for these modulators were identified through molecular docking experiments. The binding sites were further mapped to the agonist or antagonist activity reported for these molecules in literature. MD simulations were performed to evaluate the effect of ligand binding on conformational changes in the receptor, specifically the transmembrane domain. A peptidomimetic library was screened using these binding sites. Six peptidomimetics that interacted with the residues of transmembrane domain and extracellular loops were evaluated for binding activity using in vitro cAMP assay. Two of the six peptidomimetics exhibited positive allosteric modulatory activity and four peptidomimetics exhibited negative allosteric modulatory activity. All six peptidomimetics interacted with Asp521 of hFSHR(TMD). Several of the experimentally known LMW FSHR modulators also participated in H-bond interactions with Asp521, suggesting its important role in FSHR modulatory activity.

FSHR antagonists can trigger a PCOS-like state.

Over the recent years, FSHR has become an important target for development of fertility regulating agents, as impairment of FSH-FSHR interaction can lead to subfertility or infertility. In our previous study, we identified a 9-mer peptide (FSHß (89-97)) that exhibited FSHR antagonist activity. The histopathological and biochemical observations indicated, in addition to FSHR antagonism, a striking resemblance to a PCOS-like state. These observations led us to hypothesize that use of FSHR antagonists can trigger a PCOS-like state. In the present study, to validate this hypothesis, we performed qRT-PCR validation using ovarian tissue samples from our previous study. Expression of three genes known to be differentially expressed in PCOS was evaluated and found to be similar to the PCOS state. To further test the hypothesis, theoretical simulations were carried out by using the human menstrual cycle model available in the literature. Model simulations for FSHR antagonism were indicative of increased testosterone levels, increased ratio of luteinizing hormone/follicle stimulating hormone, and stockpiling of secondary follicles, which are typical characteristics of PCOS. The findings of this study will be relevant while reviewing the utility of FSHR antagonists for fertility regulation and reproductive medicine.Abbreviations: FSH: Follicle-stimulating hormone; FSHR: Follicle-stimulating hormone receptor; cAMP: Cyclic adenosine 3'5' monophosphate; PKA: Protein kinase A; PI3K: Phosphoinositide 3-kinase; PKB: protein kinase B; ERK1/2: Extracellular signal-regulated protein kinase 1/2; MAPK: Mitogen-activated protein kinases; T: testosterone; E2: estradiol; PCOS: Polycystic ovarian syndrome; LH: luteinizing hormone; Lhcgr: luteinizing hormone/choriogonadotropin receptor; CYP17A1: cytochrome P450 family 17 subfamily A member 1; Inhba: inhibin subunit beta A; qRT-PCR: Real-Time quantitative reverse transcription polymerase chain reaction; FSHß: Follicle-stimulating hormone ß subunit; Ct: Cycle threshold; Rn18s: Rattus norvegicus 18S ribosomal RNA.

Human Properdin Released By Infiltrating Neutrophils Can Modulate Influenza A Virus Infection.

The complement system is designed to recognise and eliminate invading pathogens via activation of classical, alternative and lectin pathways. Human properdin stabilises the alternative pathway C3 convertase, resulting in an amplification loop that leads to the formation of C5 convertase, thereby acting as a positive regulator of the alternative pathway. It has been noted that human properdin on its own can operate as a pattern recognition receptor and exert immune functions outside its involvement in complement activation. Properdin can bind directly to microbial targets via DNA, sulfatides and glycosaminoglycans, apoptotic cells, nanoparticles, and well-known viral virulence factors. This study was aimed at investigating the complement-independent role of properdin against Influenza A virus infection. As one of the first immune cells to arrive at the site of IAV infection, we show here that IAV challenged neutrophils released properdin in a time-dependent manner. Properdin was found to directly interact with haemagglutinin, neuraminidase and matrix 1 protein Influenza A virus proteins in ELISA and western blot. Furthermore, modelling studies revealed that properdin could bind HA and NA of the H1N1 subtype with higher affinity compared to that of H3N2 due to the presence of an HA cleavage site in H1N1. In an infection assay using A549 cells, properdin suppressed viral replication in pH1N1 subtype while promoting replication of H3N2 subtype, as revealed by qPCR analysis of M1 transcripts. Properdin treatment triggered an anti-inflammatory response in H1N1-challenged A549 cells and a pro-inflammatory response in H3N2-infected cells, as evident from differential mRNA expression of TNF-α, NF-κB, IFN-α, IFN-ß, IL-6, IL-12 and RANTES. Properdin treatment also reduced luciferase reporter activity in MDCK cells transduced with H1N1 pseudotyped lentiviral particles; however, it was increased in the case of pseudotyped H3N2 particles. Collectively, we conclude that infiltrating neutrophils at the site of IAV infection can release properdin, which then acts as an entry inhibitor for pandemic H1N1 subtype while suppressing viral replication and inducing an anti-inflammatory response. H3N2 subtype can escape this immune restriction due to altered haemagglutinin and neuraminindase, leading to enhanced viral entry, replication and pro-inflammatory response. Thus, depending on the subtype, properdin can either limit or aggravate IAV infection in the host.

Comparison of machine learning algorithms applied to symptoms to determine infectious causes of death in children: national survey of 18,000 verbal autopsies in the Million Death Study in India.

BACKGROUND: Machine learning (ML) algorithms have been successfully employed for prediction of outcomes in clinical research. In this study, we have explored the application of ML-based algorithms to predict cause of death (CoD) from verbal autopsy records available through the Million Death Study (MDS). METHODS: From MDS, 18826 unique childhood deaths at ages 1-59 months during the time period 2004-13 were selected for generating the prediction models of which over 70% of deaths were caused by six infectious diseases (pneumonia, diarrhoeal diseases, malaria, fever of unknown origin, meningitis/encephalitis, and measles). Six popular ML-based algorithms such as support vector machine, gradient boosting modeling, C5.0, artificial neural network, k-nearest neighbor, classification and regression tree were used for building the CoD prediction models. RESULTS: SVM algorithm was the best performer with a prediction accuracy of over 0.8. The highest accuracy was found for diarrhoeal diseases (accuracy = 0.97) and the lowest was for meningitis/encephalitis (accuracy = 0.80). The top signs/symptoms for classification of these CoDs were also extracted for each of the diseases. A combination of signs/symptoms presented by the deceased individual can effectively lead to the CoD diagnosis. CONCLUSIONS: Overall, this study affirms that verbal autopsy tools are efficient in CoD diagnosis and that automated classification parameters captured through ML could be added to verbal autopsies to improve classification of causes of death.

Central residues of FSHß (89-97) peptide are not critical for FSHR binding: Implications for peptidomimetic design.

In our previous study, we had identified a 9-mer peptide (FSHß (89-97)) derived from seat belt loop of human FSHß and demonstrated its ability to function as FSHR antagonist in vivo. Structure analysis revealed that the four central residues 91STDC94 within this peptide may not be critical for receptor binding. In the present study, 91STDC94 residues were substituted with alanine to generate ΔFSHß 89-97(91STDC94/AAAA) peptide. Analogous to the parent peptide, ΔFSHß 89-97(91STDC94/AAAA) peptide inhibited binding of iodinated FSH to rat FSHR and reduced FSH-induced cAMP production. The peptide could impede granulosa cell proliferation leading to reduction in FSH-mediated ovarian weight gain in immature female rats. In these rats, peptide administration further downregulated androgen receptor and estrogen receptor-alpha expression and upregulated estrogen receptor-beta expression. The results indicate that substitution of 91STDC94 with alanine did not significantly alter FSHR antagonist activity of FSHß (89-97) peptide implying that these residues are not critical for FSH-FSHR interaction and can be replaced with non-peptidic moieties for development of more potent peptidomimetics.

A Recombinant Fragment of Human Surfactant Protein D Binds Spike Protein and Inhibits Infectivity and Replication of SARS-CoV-2 in Clinical Samples.

Coronavirus disease (COVID-19) is an acute infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Human SP-D (surfactant protein D) is known to interact with the spike protein of SARS-CoV, but its immune surveillance against SARS-CoV-2 is not known. The current study aimed to examine the potential of a recombinant fragment of human SP-D (rfhSP-D) as an inhibitor of replication and infection of SARS-CoV-2. The interaction of rfhSP-D with the spike protein of SARS-CoV-2 and human ACE-2 (angiotensin-converting enzyme 2) receptor was predicted via docking analysis. The inhibition of interaction between the spike protein and ACE-2 by rfhSP-D was confirmed using direct and indirect ELISA. The effect of rfhSP-D on replication and infectivity of SARS-CoV-2 from clinical samples was assessed by measuring the expression of RdRp gene of the virus using quantitative PCR. In silico interaction studies indicated that three amino acid residues in the receptor-binding domain of spike protein of SARS-CoV-2 were commonly involved in interacting with rfhSP-D and ACE-2. Studies using clinical samples of SARS-CoV-2-positive cases (asymptomatic, n = 7; symptomatic, n = 8) and negative control samples (n = 15) demonstrated that treatment with 1.67 µM rfhSP-D inhibited viral replication by ∼5.5-fold and was more efficient than remdesivir (100 µM) in Vero cells. An approximately two-fold reduction in viral infectivity was also observed after treatment with 1.67 µM rfhSP-D. These results conclusively demonstrate that the rfhSP-D mediated calcium independent interaction between the receptor-binding domain of the S1 subunit of the SARS-CoV-2 spike protein and human ACE-2, its host cell receptor, and significantly reduced SARS-CoV-2 infection and replication in vitro.

Enrichment analyses of diseases and pathways associated with precocious puberty using PrecocityDB.

Precocious puberty (PP) is an important endocrine disorder affecting children globally. Several genes, SNPs and comorbidities are reported to be associated with PP; however, this data is scattered across scientific literature and has not been systematically collated and analysed. In this study, we present PrecocityDB as the first manually curated online database on genes and their ontology terms, SNPs, and pathways associated with PP. A tool for visualizing SNP coordinates and allelic variation on each chromosome, for genes associated with PP is also incorporated in PrecocityDB. Pathway enrichment analysis of PP-associated genes revealed that endocrine and cancer-related pathways are highly enriched. Disease enrichment analysis indicated that individuals with PP seem to be highly likely to suffer from reproductive and metabolic disorders such as PCOS, hypogonadism, and insulin resistance. PrecocityDB is a useful resource for identification of comorbid conditions and disease risks due to shared genes in PP. PrecocityDB is freely accessible at http://www.precocity.bicnirrh.res.in . The database source code and content can be downloaded through GitHub ( https://github.com/bic-nirrh/precocity ).

Exploring the druggable proteome of Candida species through comprehensive computational analysis.

Candida albicans and non-albicans Candida spp. are major cause of systemic mycoses. Antifungal drugs such as azoles and polyenes are not efficient to successfully eradicate Candida infection owing to their fungistatic nature or low bioavailability. Here, we have adopted a comprehensive computational workflow for identification, prioritization and validation of targets from proteomes of Candida albicans and Candida tropicalis. The protocol involves identification of essential drug-target candidates using subtractive genomics, protein-protein interaction network properties and systems biology based methods. The essentiality of the novel metabolic and non-metabolic targets was established by performing in silico gene knockouts, under aerobic as well as anaerobic conditions, and in vitro drug inhibition assays respectively. Deletion of twelve genes that are involved in amino acid, secondary metabolite, and carbon metabolism showed zero growth in metabolic model under simulated conditions. The algorithm, used in this study, can be downloaded from http://pbit.bicnirrh.res.in/offline.php and executed locally.

A 5-mer peptide derived from hinge region of hFSHR can function as positive allosteric modulator in vivo.

Interaction of follicle stimulating hormone (FSH) with its cognate receptor (FSHR) is critical for maintaining reproductive health. FSHR has a large extracellular domain (ECD), composed of leucine rich repeats (LRRs) and hinge region, a transmembrane domain (TMD) and a short C-terminal domain (CTD). In this study, we have identified a short peptidic stretch in the hinge region (hFSHR(271-275)), through extensive computational modeling, docking and MD simulations, that is capable of independently interacting with the extracellular loops of FSHR(TMD). In vitro studies revealed that FSHR(271-275) peptide increased binding of [125I]-FSH to rat Fshr as well as FSH-induced cAMP production. Administration of FSHR(271-275) peptide in immature female rats significantly increased FSH-mediated ovarian weight gain and promoted granulosa cell proliferation. In summary, the results demonstrate that the synthetic peptide corresponding to amino acids 271-275 of hFSHR-hinge region stimulates FSH-FSHR interaction and behaves as positive allosteric modulator of FSHR. The study also lends evidence to the existing proposition that hinge region maintains the receptor in an inactive conformation in the absence of its ligand by engaging in intramolecular interactions with extracellular loops of TMD.