Determination of mosquito Larvicidal potential of Bacillus thuringiensis Cry11Ba fusion protein through molecular docking

Evaluating the role of trypsin in silk degumming: An in silico approach

The trypsin being universal enzyme forming family of proteases catalyzes the hydrolysis of proteins into amino acids and regenerates the serine hydroxyl an active site. The trypsin enzyme from D. saccharalis, uses sericin as its preferred substrate. Presence of catalytic triad (serine, aspartic acid and histidine) at the substrate binding site of this enzyme is very important for the catalytic activity. In the current study, the interacting mechanism between the substrate sericin protein and enzyme trypsin protein were explored by integrating various computational approaches including physico-chemical properties, biophysical properties, dynamics, gene ontology, molecular docking, protein - protein interactions, binding free energy calculation and structural motifs were studied. The evolutionary study performed by MEGA X showed that trypsin protein sequence (ALE15212.1) is closely related to cocoonase protein sequence (ADG26770.1) from Antheraea pernyi. 3-D models of trypsin and sericin proteins were predicted using I-TASSER and further validated by PROCHECK, and ProSAweb softwares. The predicted trypsin structure model was assigned E.C. no. 3.4.21.4 which refers hydrolytic mechanism. Gene Ontology predicted by QuickGO showed that trypsin has serine hydrolase activity (GO: 00017171), and part of proteolysis (GO: 0006508) as well as protein metabolic process (GO:0019538) actvity. Molecular docking studies between trypsin and sericin proteins were conducted by the HADDOCK 2.4 having best docked protein complex with Z-score - 1.9. 2D and 3D protein-protein interaction was performed with LIGPLOT⁺ and HAWKDOCK, PDBsum, respectively. The amino acid residues interacting across proteins interface are sericin_chain A representing "Ser133, Tyr214, Thr188, Thr243, Ser225, Ser151, Ser156, His294, Arg293, Gly296″ and trypsin_chain B "Lys120, Tyr246, Asn119, Glu239, Ser62, Tyr194, Ile197, Ser171, Tyr169, Gly170″. Based on our results trypsin shows similarity with cocoonase and presumably trypsin can be used as an alternative source in cocoon degumming.

Exploration of insecticidal potential of Cry protein purified from Bacillus thuringiensis VIID1

Insect pests are a threat to agriculture as they cause a loss of 15-22% to economically important crops every year. Bacillus thuringiensis produces parasporal crystal inclusions that have insecticidal 'Cry' proteins which are toxic to insect larvae of the order Lepidoptera, Coleoptera and Diptera, etc. In the present study, 40 different soil samples from Amritsar and its surrounding areas were selected for isolation of B. thuringiensis. The rod shaped, gram-positive bacterial isolates were further analyzed for characteristic crystal formation using phase contrast and scanning electron microscopy. 6 Bacillus samples containing cry genes were identified using the universal primers for cry genes, of which one isolate exhibited a protein band of ~95 kDa. This protein was purified using a Sephadex G-75 column. The insecticidal assays conducted with purified Cry protein on insect larvae of lepidopteran and dipteran orders viz. Spodoptera litura, Galleria malonella, Bactrocera cucurbitae and Culex pipens revealed considerable detrimental effects. A significant increase in larval mortality was observed for the larvae of all insects in a concentration dependent manner when treated with Cry protein purified from B. thuringenisis VIID1. The purified Cry protein did not have any significant effect on honey bee larvae.