@article { ISI:000353901700002, title = {Insect trehalase: physiological significance and potential applications}, journal = {Glycobiology}, volume = {25}, number = {4}, year = {2015}, month = {APR}, pages = {357-367}, publisher = {OXFORD UNIV PRESS INC}, address = {JOURNALS DEPT, 2001 EVANS RD, CARY, NC 27513 USA}, abstract = {

Trehalose, a non-reducing disaccharide, is widespread throughout the biological world. It is the major blood sugar in insects playing a crucial role as an instant source of energy and in dealing with abiotic stresses. The hydrolysis of trehalose is under the enzymatic control of trehalase. The enzyme trehalase is gaining interest in insect physiology as it regulates energy metabolism and glucose generation via trehalose catabolism. The two forms of insect trehalase namely, Tre-1 and Tre-2, are important in energy supply, growth, metamorphosis, stress recovery, chitin synthesis and insect flight. Insect trehalase has not been reviewed in depth and the information available is quite scattered. The present mini review discusses our recent understanding of the regulation, mechanism and biochemical characterization of insect trehalase with respect to its physiological role in vital life functions. We also highlight the molecular and biochemical properties of insect trehalase that makes it amenable to competitive inhibition by most glycosidase inhibitors. Due to its crucial role in carbon metabolism in insects, application of inhibitors against trehalose can form a promising area towards formulating strategies for insect pest control.

}, keywords = {carbohydrate metabolism, glycosidase inhibitor, glycoside hydrolase, trehalase, trehalose}, issn = {0959-6658}, doi = {10.1093/glycob/cwu125}, author = {Shukla, Ekta and Thorat, Leena J. and Nath, Bimalendu B. and Gaikwad, Sushama M.} } @article {43444, title = {Molecular cloning and in silico studies of physiologically significant trehalase from drosophila melanogaster}, journal = {International Journal of Biological Macromolecules}, volume = {92}, year = {2016}, month = {NOV}, pages = {282-292}, abstract = {Trehalase, a physiologically important glycosidase is known for its crucial role in insect glycometabolism and stress recovery. The present study describes the molecular cloning of a gene fragment, encoding the catalytically active trehalase from Drosophila melanogaster (DmTre) and its heterologous expression in Escherichia coli. The 1275 bp gene was overexpressed in two different vectors viz., pET28a and pCOLD TF and investigated for variable soluble expression, purification and activity of the recombinant enzyme with optimum pH and temperature of enzyme as 6 and 55 degrees C, respectively. The sequence was characterized in silico by subjecting it to homology search, multiple sequence alignment and phylogenetic tree construction revealing its identity to other trehalases which belong to glycoside hydrolase family 37. The deduced amino acid sequence and modeled 3D structure of DmTre possessed all features of trehalase superfamily, including signature motifs and catalytic domain. The active site pocket of recombinant DmTre was compared with the crystal structure of E. coli trehalase identifying Glu424 and Asp226 as the putative catalytic residues. Additionally, enzyme-substrate docking suggests possible involvement of other residues in the catalysis along with Asp226. The present study holds significance in understanding the structural aspects of Drosophila trehalase in spite of unavailabilty of eukaryotic trehalase crystal structure. (C) 2016 Elsevier B.V. All rights reserved.}, doi = {10.1016/j.ijbiomac.2016.06.097}, author = {Shukla, Ekta and Thorat, Leena and Bhavnani, Varsha and Bendre, Ameya D. and Pal, J. K. and Nath, B. B. and Gaikwad, Sushama M.} } @article {43519, title = {Conformational and functional transitions and in silico analysis of a serine protease from conidiobolus brefeldianus (MTCC 5185)}, journal = {International Journal of Biological Macromolecules}, volume = {98}, year = {2017}, month = {MAY}, pages = {387-397}, abstract = {This work describes functional and structural transitions of a novel protease isolated from Conidiobolus brefeldianus MTCC 5185 (Cprot), in detail using biophysical and bioinformatics tools. The commercial importance of Cprot in silk and leather industries made it an interesting candidate for structural investigations. Cprot possesses 8.2\%alpha-helix, 31.1\% beta-sheet and 23.8\% turns. The enzyme was found to be active over a wide pH range and up to 55 degrees C. The protease was also stable in organic solvents up to 50\% (v/v) concentration of alcohols and DMSO for >24 h and in 2 M guanidine hydrochloride for >12 h. Cprot was also resistant to trypsin, chymotrypsin, proteinase K and fluorinated alcohols (5-10\%). The melting temperatures observed for the native Cprot and for the enzyme treated under various stress conditions correlated well with the corresponding structural and functional transitions obtained. The structural information was supported by the homology model of its closest homologue from C. coronatus; revealing its similarity to PA clan of proteases (Proteases of mixed nucleophile, superfamily A), with His-64, Asp-113 and Ser-208 as putative catalytic triad. Three tryptophan residues in Cprot are surrounded by positively charged residues, as evident from solute quenching studies and homology model. (C) 2017 Elsevier B.V. All rights reserved.}, doi = {10.1016/j.ijbiomac.2017.01.124}, author = {Shukla, Ekta and Agrawal, Sanskruthi B. and Gaikwad, Sushama M.} } @article {44651, title = {Cloning and characterization of trehalase: a conserved glycosidase from oriental midge, Chironomus ramosus}, journal = {3 Biotech}, volume = {8}, year = {2018}, month = {AUG}, pages = {352}, abstract = {

Insect trehalase is a multiferous enzyme, crucial for normal physiological functions as well as under stress conditions. In this report, we present a fundamental study of the trehalase gene segment (1587 bp) from Chironomus ramosus (CrTre) encoding for 529 amino acids, using appropriate bioinformatics tools. C. ramosus, a tropical midge is an emerging animal model to investigate the consequences of environmental stresses. We observed that CrTre belongs to GH family 37 in the CAZy database and possess 57-92\% identity to dipteran trehalases. In silico characterization provided information regarding the structural, functional and evolutionary aspects of midge trehalase. In the phylogenetic tree, CrTre clustered with the soluble dipteran trehalases. Moreover, domain functional characterization of the deduced protein sequence by InterProScan (IPR001661), ProSite (PS00927 and PS00928) and Pfam (PF01204) indicated presence of highly conserved signature motifs which are important for the identification of trehalase superfamily. Furthermore, the instability index of CrTre was predicted to be \< 40 suggesting its in vivo stability while, the high aliphatic index indicated towards its thermal stability (index value 71-81). The modelled 3D tertiary structure of CrTre depicts a (alpha/alpha)(6) barrel toroidal core. The catalytic domain of the enzyme comprised Glu424 and Asp226 as the putative active site residues. Interestingly, the conserved motifs were observed to be formed by the flexible loopy regions in the tertiary structure. This study revealed essential sequence features of the midge trehalase and offers better insights into the structural aspects of this enzyme which can be correlated with its function.

}, keywords = {Conserved motifs, Homology modelling, Midges, Secondary structure, trehalose}, issn = {2190-572X}, doi = {10.1007/s13205-018-1376-y}, author = {Shukla, Ekta and Thorat, Leena and Bendre, Ameya D. and Jadhav, Santosh and Pal, Jayanta K. and Nath, Bimalendu B. and Gaikwad, Sushama M.} } @article {45386, title = {The Leishmania donovani IMPACT-like protein possesses non-specific nuclease activity}, journal = {International Journal of Biological Macromolecules}, volume = {119}, year = {2018}, month = {NOV}, pages = {962-973}, type = {Article}, abstract = {IMPACT (Imprinted and Ancient)-like proteins are known to be regulators of GCN2 (General control non-derepressible 2) kinases involved in translation regulation. Here, we report on cloning and characterization of an IMPACT-like protein, LdIMPACT from Leishmania donovani which harbours two domains. {\textquoteright}RWD domain{\textquoteright} at the N-terminal end that mediates GCN2 regulation, while a conserved {\textquoteright}ancient domain{\textquoteright} lies at the C-terminal end whose function remains elusive. Interestingly, our observations indicated that LdIMPACT has a novel nonspecific nuclease activity. In silico analysis further revealed the resemblance of ancient domain of LdIMPACT to RNase PH domain (known to bind to nucleic acids). The recombinant LdIMPACT exhibited a Mg2+-dependent nuclease activity. Moreover, thermostability and pH stability assays of the protein suggest it to be a stress responsive protein. Circular dichroism studies elucidated the conformational transitions of the enzyme in response to various temperature and pH conditions which correlated well with the activity profiles. Thus, the current study highlights the structural and functional characteristics of LdIMPACT which interestingly also possesses a novel nuclease activity. With its physiological relevance unresolved, the multifaceted LdIMPACT might therefore lie in a hitherto unknown network, whose perturbation could be an attractive therapeutic approach for treating leishmaniasis. (C) 2018 Elsevier B.V. All rights reserved.}, issn = { 0141-8130}, doi = {10.1016/j.ijbiomac.2018.07.175}, author = {Rao, Shilpa J. and Shukla, Ekta and Bhatia, Varsha and Lohiya, Bharat and Gaikwad, Sushama M. and Kar, Anita and Pal, Jayanta K.} } @article {46785, title = {Functional stability and structural transitions of a kunitz trypsin inhibitor from chickpea (CaTI2)}, journal = {Protein Journal}, volume = {39}, year = {2020}, month = {AUG}, pages = {350-357}, type = {Article}, abstract = {

Enzymes are important tools for various applications. We have studied structural transitions and functional stability of a Kunitz trypsin inhibitor from Chickpea (CaTI2), a potent insect gut-protease inhibitor, under different stress conditions like non-neutral pH, elevated temperature and co-solvent concentrations. CaTI2 was cloned and expressed in an eukaryotic systemP. pastorisand was investigated for conformational transitions using circular dichroism spectroscopy, differential scanning fluorimetry and activity assay. Native CaTI2 has a sheet dominant structure with 40\% beta sheets and possess a single tryptophan residue situated in the hydrophobic core of the enzyme. The recombinant inhibitor maintained its maximum activity under alkaline pH with its secondary structure intact between pH 6-10. CaTI2 was observed to be thermally stable up to 55 degrees C with aT(m) of 61.3 degrees C above which the protein unfolds. On treating with chemical denaturant (urea), the CaTI2 lost its inhibitory potential and native conformation beyond 2 M urea concentration. Moreover, the protein unfolded at lower temperatures as the concentration of denaturant increased, suggesting more complex structural changes. Further, the stability of the inhibitor was found to be directly proportional to the solvent polarity. The data, herein offers significant information of inhibitor stability and activity which could be exploited for its further development into an effective pesticide. [GRAPHICS] .

}, keywords = {Chickpea, Circular dichroism spectroscopy, Differential scanning fluorimetry, Functional stability, Kunitz trypsin inhibitor}, issn = {1572-3887}, doi = {10.1007/s10930-020-09911-2, Early Access Date = JUL 2020}, author = {Bendre, Ameya D. and Shukla, Ekta and Ramasamy, Sureshkumar} } @article {46636, title = {Structural and physical analysis of underwater silk from housing nest composites of a tropical chironomid midge}, journal = {International Journal of Biological Macromolecules}, volume = {163}, year = {2020}, month = {NOV }, pages = {934-942}, type = {Article}, abstract = {

Chironomids are an abundant group of aquatic silk spinning insects. They offer a unique opportunity of silk harvestation without killing them; however, they remained underappreciated models in silk research. Here, we investigate the structural and biomechanical characteristics of silk from the midge, Chironomus ramosus. A combination of microscopic (SEM), spectroscopic (CD and IR), structural (XRD), thermal (DSC and TGA) and mechanical measurement tools and techniques were employed to gain critical insights on midge silk. Maximum yield of silk was obtained from Chironomus in similar to 2.5 h, the shortest time reported among insects. The network of water-insoluble silk fibres possessed the smallest diameter of 110 +/- 35 nm, known for any insect silk, qualifying its superiority in fibre fineness. We demonstrate a cruelty-free silk extraction method in contrast to the conventional violent techniques. Structural characterization indicated coexistence of various secondary conformations, beta sheets being predominant. We compare and contrast these features to well-characterized caddisfly and silk-worm silks and highlight the uniqueness in midge silk that render mechanical stability and potentially contribute to its multi-functionalization. We thus propose Chironomus as an emerging candidate of water-borne silk, especially in the context of the {\textquoteleft}Peace silk{\textquoteright} industry, aiming to develop non-violent methods for silk harvestation from animals. (C) 2020 Elsevier B.V. All rights reserved.

}, keywords = {biopolymer, Chironomus, Commercial applications, Housing nest composite, Peace silk, Underwater silk}, issn = {0141-8130}, doi = {10.1016/j.ijbiomac.2020.07.070}, author = {Thorat, Leena and Joseph, Emmanuel and Nisal, Anuya and Shukla, Ekta and RaviKumar, Ameeta and Nath, Bimalendu B.} }