@article {130540, title = {Influence of pH on indole-dependent heterodimeric interactions between Anopheles gambiae odorant-binding proteins OBP1 and OBP4.}, journal = {Int J Biol Macromol}, year = {2023}, month = {2023 Jun 15}, pages = {125422}, abstract = {

Insect Odorant Binding Proteins (OBPs) constitute important components of their olfactory apparatus, as they are essential for odor recognition. OBPs undergo conformational changes upon pH change, altering their interactions with odorants. Moreover, they can form heterodimers with novel binding characteristics. Anopheles gambiae OBP1 and OBP4 were found capable of forming heterodimers possibly involved in the specific perception of the attractant indole. In order to understand how these OBPs interact in the presence of indole and to investigate the likelihood of a pH-dependent heterodimerization mechanism, the crystal structures of OBP4 at pH 4.6 and 8.5 were determined. Structural comparison to each other and with the OBP4-indole complex (3Q8I, pH 6.85) revealed a flexible N-terminus and conformational changes in the α4-loop-α5 region at acidic pH. Fluorescence competition assays showed a weak binding of indole to OBP4 that become further impaired at acidic pH. Additional Molecular Dynamic and Differential Scanning Calorimetry studies displayed that the influence of pH on OBP4 stability is significant compared to the modest effect of indole. Furthermore, OBP1-OBP4 heterodimeric models were generated at pH 4.5, 6.5, and 8.5, and compared concerning their interface energy and cross-correlated motions in the absence and presence of indole. The results indicate that the increase in pH may induce the stabilization of OBP4 by increasing its helicity, thereby enabling indole binding at neutral pH that further stabilizes the protein and possibly promotes the creation of a binding site for OBP1. A decrease in interface stability and loss of correlated motions upon transition to acidic pH may provoke the heterodimeric dissociation allowing indole release. Finally, we propose a potential OBP1-OBP4 heterodimer formation/disruption mechanism induced by pH change and indole binding.

}, issn = {1879-0003}, doi = {10.1016/j.ijbiomac.2023.125422}, author = {Mam, Bhavika and Tsitsanou, Katerina E and Liggri, Panagiota G V and Saitta, Francesca and Stamati, Evgenia C V and Mahita, Jarjapu and Leonis, George and Drakou, Christina E and Papadopoulos, Manthos and Arnaud, Philippe and Offmann, Bernard and Fessas, Dimitrios and Sowdhamini, Ramanathan and Zographos, Spyros E} } @article {78096, title = {Dataset for the combined transcriptome assembly of and functional annotation.}, journal = {Data Brief}, volume = {30}, year = {2020}, month = {2020 Jun}, pages = {105416}, abstract = {

In this paper, we present the data acquired during transcriptome analysis of the Moringa oleifera [1] from five different tissues (root, stem, leaf, flower and seed) by RNA sequencing. A total of 271 million reads were assembled with an N50 of 2094 bp. The combined transcriptome was assessed for transcript abundance across five tissues. The protein coding genes identified from the transcripts were annotated and used for orthology analysis. Further, enzymes involved in the biosynthesis of select medicinally important secondary metabolites, vitamins and ion transporters were identified and their expression levels across tissues were examined. The data generated by RNA sequencing has been deposited to NCBI public repository under the accession number PRJNA394193 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA394193).

}, issn = {2352-3409}, doi = {10.1016/j.dib.2020.105416}, author = {Shafi, K Mohamed and Joshi, Adwait G and Meenakshi, Iyer and Pasha, Shaik Naseer and Harini, K and Mahita, Jarjapu and Sajeevan, Radha Sivarajan and Karpe, Snehal D and Ghosh, Pritha and Nitish, Sathyanarayanan and Gandhimathi, A and Mathew, Oommen K and Prasanna, Subramanian Hari and Malini, Manoharan and Mutt, Eshita and Naika, Mahantesha and Ravooru, Nithin and Rao, Rajas M and Shingate, Prashant N and Sukhwal, Anshul and Sunitha, Margaret S and Upadhyay, Atul K and Vinekar, Rithvik S and Sowdhamini, Ramanathan} } @article {83641, title = {A knowledge-driven protocol for prediction of proteins of interest with an emphasis on biosynthetic pathways.}, journal = {MethodsX}, volume = {7}, year = {2020}, month = {2020}, pages = {101053}, abstract = {

This protocol describes a stepwise process to identify proteins of interest from a query proteome derived from NGS data. We implemented this protocol on transcriptome to identify proteins involved in secondary metabolite and vitamin biosynthesis and ion transport. This knowledge-driven protocol identifies proteins using an integrated approach involving sensitive sequence search and evolutionary relationships. We make use of functionally important residues (FIR) specific for the query protein family identified through its homologous sequences and literature. We screen protein hits based on the clustering with true homologues through phylogenetic tree reconstruction complemented with the FIR mapping. The protocol was validated for the protein hits through qRT-PCR and transcriptome quantification. Our protocol demonstrated a higher specificity as compared to other methods, particularly in distinguishing cross-family hits. This protocol was effective in transcriptome data analysis of as described in Pasha et al.{\textbullet}Knowledge-driven protocol to identify secondary metabolite synthesizing protein in a highly specific manner.{\textbullet}Use of functionally important residues for screening of true hits.{\textbullet}Beneficial for metabolite pathway reconstruction in any (species, metagenomics) NGS data.

}, issn = {2215-0161}, doi = {10.1016/j.mex.2020.101053}, author = {Joshi, Adwait G and Harini, K and Meenakshi, Iyer and Shafi, K Mohamed and Pasha, Shaik Naseer and Mahita, Jarjapu and Sajeevan, Radha Sivarajan and Karpe, Snehal D and Ghosh, Pritha and Nitish, Sathyanarayanan and Gandhimathi, A and Mathew, Oommen K and Prasanna, Subramanian Hari and Malini, Manoharan and Mutt, Eshita and Naika, Mahantesha and Ravooru, Nithin and Rao, Rajas M and Shingate, Prashant N and Sukhwal, Anshul and Sunitha, Margaret S and Upadhyay, Atul K and Vinekar, Rithvik S and Sowdhamini, Ramanathan} } @article {57789, title = {The transcriptome enables the identification of candidate genes behind medicinal value of Drumstick tree (Moringa oleifera).}, journal = {Genomics}, volume = {112}, year = {2020}, month = {01/2020}, pages = {621-628}, abstract = {

Moringa oleifera is a plant well-known for its nutrition value, drought resistance and medicinal properties. cDNA libraries from five different tissues (leaf, root, stem, seed and flower) of M. oleifera cultivar Bhagya were generated and sequenced. We developed a bioinformatics pipeline to assemble transcriptome, along with the previously published M. oleifera genome, to predict 17,148 gene models. Few candidate genes related to biosynthesis of secondary metabolites, vitamins and ion transporters were identified. Expressions were further confirmed by real-time quantitative PCR experiments for few promising leads. Quantitative estimation of metabolites, as well as elemental analysis, was also carried out to support our observations. Enzymes in the biosynthesis of vitamins and metabolites like quercetin and kaempferol are highly expressed in leaves, flowers and seeds. The expression of iron transporters and calcium storage proteins were observed in root and leaves. In general, leaves retain the highest amount of small molecules of interest.

}, issn = {1089-8646}, doi = {10.1016/j.ygeno.2019.04.014}, author = {Pasha, Shaik Naseer and Shafi, K Mohamed and Joshi, Adwait G and Meenakshi, Iyer and Harini, K and Mahita, Jarjapu and Sajeevan, Radha Sivarajan and Karpe, Snehal D and Ghosh, Pritha and Nitish, Sathyanarayanan and Gandhimathi, A and Mathew, Oommen K and Prasanna, Subramanian Hari and Malini, Manoharan and Mutt, Eshita and Naika, Mahantesha and Ravooru, Nithin and Rao, Rajas M and Shingate, Prashant N and Sukhwal, Anshul and Sunitha, Margaret S and Upadhyay, Atul K and Vinekar, Rithvik S and Sowdhamini, Ramanathan} } @article {43842, title = {Vaccination and immunization strategies to design Aedes aegypti salivary protein based subunit vaccine tackling Flavivirus infection.}, journal = {Int J Biol Macromol}, volume = {122}, year = {2019}, month = {2018 Sep 13}, pages = {1203-1211}, abstract = {

Flavivirus causes arthropod-borne severe diseases that sometimes lead to the death. The Flavivirus species including Dengue virus, Zika virus and yellow fever virus are transmitted by the bite of Aedes mosquitoes. All these viral species target the people living in their respective endemic zone causing a high mortality rate. Recent studies show that immune factors present in the Ae. aegypti saliva is the hidden culprit promoting blood meal collection, suppressing host immune molecules and promoting disease establishment. This study was designed to develop a subunit vaccine using Aedes mosquito salivary proteins targeting the aforementioned Flaviviruses. Subunit vaccine was designed very precisely by combining the immunogenic B-cell epitope with CTL and HTL epitopes and also suitable adjuvant and linkers. Immunogenicity, allergenicity and physiochemical characterization were also performed for scientific validation. Molecular docking and molecular dynamics simulations studies were carried out to confirm the stable affinity between the vaccine protein (3D) and TLR3 receptor. At last, in silico cloning was executed to get the subunit vaccine restriction clone into pET28a vectro to express it in microbial expression system. Additionally, this study warrants the experimental evaluation for the validation purposes.

}, issn = {1879-0003}, doi = {10.1016/j.ijbiomac.2018.09.071}, author = {Pandey, Rajan Kumar and Dahiya, Surbhi and Mahita, Jarjapu and Sowdhamini, Ramanathan and Prajapati, Vijay Kumar} } @article {29621, title = {Investigating the effect of key mutations on the conformational dynamics of Toll-like receptor dimers through molecular dynamics simulations and protein structure networks.}, journal = {Proteins}, year = {2018}, month = {2018 Jan 31}, abstract = {

The Toll-like receptors (TLRs) are critical components of the innate immune system due to their ability to detect conserved pathogen-associated molecular patterns, present in bacteria, viruses and other microorganisms. Ligand detection by TLRs leads to a signalling cascade, mediated by interactions among TIR domains present in the receptors, the bridging adaptors as well as sorting adaptors. The BB loop is a highly conserved region present in the TIR domain and is crucial for mediating interactions among TIR domain-containing proteins. Mutations in the BB loop of the Toll-like receptors, such as the A795P mutation in TLR3 and the P712H mutation (Lpsd mutation) in TLR4, have been reported to disrupt or alter downstream signalling. While the phenotypic effect of these mutations is known, the underlying effect of these mutations on the structure, dynamics and interactions with other TIR domain-containing proteins is not well understood. Here, we have attempted to investigate the effect of the BB loop mutations on the dimer form of TLRs, using TLR2 and TLR3 as case studies. Our results based on molecular dynamics simulations, protein-protein interaction analyses and protein structure network analyses highlight significant differences between the dimer interfaces of the wild-type and mutant forms and provide a logical reasoning for the effect of these mutations on adaptor binding to TLRs. Furthermore, it also leads us to propose a hypothesis for the differential requirement of signalling and bridging adaptors by TLRs. This could aid in further understanding of the mechanisms governing such signalling pathways. This article is protected by copyright. All rights reserved.

}, issn = {1097-0134}, doi = {10.1002/prot.25467}, author = {Mahita, Jarjapu and Sowdhamini, Ramanathan} } @article {29620, title = {Probing subtle conformational changes induced by phosphorylation and point mutations in the TIR domains of TLR2 and TLR3.}, journal = {Proteins}, year = {2018}, month = {2018 Jan 31}, abstract = {

Extensive research performed on Toll-like receptor (TLR) signalling has identified residues in the Toll/interleukin-1 receptor (TIR) domains that are essential for its proper functioning. Among these residues, those in BB loop are particularly significant as single amino acid mutations in this region can cause drastic changes in downstream signalling. However, while the effect of these mutations on the function is well studied (like the P681H mutation in TLR2, the A795P mutation in TLR3, and the P714H mutation in TLR4), their influence on the dynamics and inter-residue networks is not well understood. The effects of local perturbations induced by these mutations could propagate throughout the TIR domain, influencing interactions with other TIR domain-containing proteins. The identification of these subtle changes in inter-residue interactions can provide new insights and structural rationale for how single-point mutations cause drastic changes in TIR-TIR interactions. We employed molecular dynamics simulations and protein structure network (PSN) analyses to investigate the structural transitions with special emphasis on TLR2 and TLR3. Our results reveal that phosphorylation of the Tyr 759 residue in the TIR domain of TLR3 introduces rigidity to its BB loop. Subtle differences in the intra BB loop hydrogen bonding network between TLR3 and TLR2 are also observed. The PSN analyses indicate that the TIR domain is highly connected and pinpoints key differences in the inter-residue interactions between the wild-type and mutant TIR domains, suggesting that TIR domain structure is prone to allosteric effects, consistent with the current view of the influence of allostery on TLR signaling. This article is protected by copyright. All rights reserved.

}, issn = {1097-0134}, doi = {10.1002/prot.25471}, author = {Mahita, Jarjapu and Sowdhamini, Ramanathan} } @article {16560, title = {Integrative modelling of TIR domain-containing adaptor molecule inducing interferon-β (TRIF) provides insights into its autoinhibited state.}, journal = {Biol Direct}, volume = {12}, year = {2017}, month = {2017 Apr 20}, pages = {9}, abstract = {

BACKGROUND: TRIF is a key protein in antiviral innate immunity, operating downstream of TLRs. TRIF activation leads to the production of interferon-β and pro-inflammatory cytokines. There is evidence from experiments to suggest that the N-terminal domain of TRIF binds to its TIR domain to avoid constitutive activation. However, no structure of a complex between the N-terminal domain and the TIR domain exists till date. The disordered nature of the region connecting the N-terminal domain and the TIR domain compounds the issue of elucidating the mechanism of autoinhibition of TRIF. In this study, we have employed an integrative approach consisting of mutual information analysis, docking, molecular dynamics simulations and residue network analysis, in combination with existing experimental data to provide a glimpse of TRIF in its autoinhibited state.

RESULTS: Our extensive docking approach reveals that the N-terminal domain binds to the BB loop-B helix region of the TIR domain, consistent with experimental observations. Long length molecular dynamics simulations of 1 microsecond performed on the docked model highlights residues participating in hydrogen bonding and hydrophobic interactions at the interface. A pair of residues present in the vicinity of the interface is also predicted by mutual information analysis, to co-evolve. Residues mediating long-range interactions within the TIR domain of TRIF were identified using residue network analysis.

CONCLUSIONS: Based on the results of the modelling and residue network analysis, we propose that the N-terminal domain binds to the BB loop region of the TIR domain, thereby preventing its homodimersation. The binding of TRIF to TLR3 or TRAM could induce a slight conformational change, causing the interactions between the N-terminal domain and TIR domain to disrupt, thereby exposing the BB loop and rendering it amenable for higher-order oligomerisation.

REVIEWERS: This article was reviewed by Michael Gromiha, Srikrishna Subramaniam and Peter Bond (nominated by Chandra Verma).

}, issn = {1745-6150}, doi = {10.1186/s13062-017-0179-0}, author = {Mahita, Jarjapu and Sowdhamini, Ramanathan} } @article {8344, title = {An in silico approach towards the identification of novel inhibitors of the TLR-4 signaling pathway.}, journal = {J Biomol Struct Dyn}, volume = {34}, year = {2016}, month = {2016 Jun}, pages = {1345-62}, abstract = {

Precise functioning and fine-tuning of Toll-like receptor 4 (TLR4) signaling is a critical requirement for the smooth functioning of the innate immune system, since aberrant TLR4 activation causes excessive production of pro-inflammatory cytokines and interferons. This can result in life threatening conditions such as septic shock and other inflammatory disorders. The TRIF-related adaptor molecule (TRAM) adaptor protein is unique to the TLR4 signaling pathway and abrogation of TRAM-mediated TLR4 signaling is a promising strategy for developing therapeutics aimed at disrupting TRAM interactions with other components of the TLR4 signaling complex. The VIPER motif from the vaccinia virus-producing protein, A46 has been reported to disrupt TRAM-TLR4 interactions. We have exploited this information, in combination with homology modeling and docking approaches, to identify a potential binding site on TRAM lined by the BB loop and αC helix. Virtual screening of commercially available small molecules targeting the binding site enabled to short-list 12 small molecules to abrogate TRAM-mediated TLR4 signaling. Molecular dynamics and molecular mechanics calculations have been performed for the analysis of these receptor-ligand interactions.

}, issn = {1538-0254}, doi = {10.1080/07391102.2015.1079243}, author = {Mahita, Jarjapu and Harini, K and Rao Pichika, Mallikarjuna and Sowdhamini, Ramanathan} }