Characterization of Bacillus thuringiensis Cry1 class proteins in relation to their insecticidal action

Abstract

Thirty nine Bt Cry1 subgroup protein sequences were retrieved from NCBI and analyzed for physicochemical properties, active site and relationship in relation to their variations in toxicity. Cry1 proteins were found to be hydrophilic and stable. SOSUI server predicted presence of two transmembrane regions in Ag and a single transmembrane region from Aa to Ae. EMBOSS PepWheel tool analysis of the transmembrane regions showed that there were 23 highly conserved residues towards the N terminal which are hydrophobic and more than half of the residues were neutrally charged. No signal peptide was detected which classifies the Cry1 group proteins as non-secretory proteins. Cry1 proteins have very high composition of neutral amino acids and might transform into negative charge after solubilization in alkaline environment (insect midgut). The negatively charged protein might misfold causing difficultly to digest and thereby be toxic to lepidopteran. Active sites of Cry1 proteins with more than 50% neutral amino acids showed wide insecticidal spectrum and further positive correlation (r = 0.7731) was observed between neutral amino acids and insect species affected (Y = -138.21 + 2.907X). Similarity of sequences was found between Cry1 proteins based on their high or low spectrum of insecticidal activity.

Bacterial imaging and photodynamic inactivation using zinc(ii)-dipicolylamine BODIPY conjugates

“…54 The crystal toxin contains high fractions of anionic aspartate and glutamate residues that attract the cationic ZnDPA unit. 55 The strong spore staining provided a low detection sensitivity of ~100 CFU/ml using the CCD experimental setup. Spores appear to possess more anionic surfaces charges compared to vegetative bacteria strains which could explain the enhanced accumulation.…”

Peptide selection and antibody generation for the prospective immunorecognition of Cry1Ab16 protein of transgenic maize

“…MON810 and Bt11 transgenic events have been widely cultivated since they present resistance to a specific insect named European corn borer, which is responsible for inducing severe damage in European maize plantations. Both transgenic maize lines were modified to express the Cry1A(b) toxin that is one of the subclasses of Cry1 proteins (ISAAA, http://www.isaaa.org; Kumar et al, 2013). Like other Cry proteins, Cry1A(b) corresponds to the final product of a protoxin of approximately 130 kDa and 1155 amino acids that, after being submitted to different mechanisms occurring at transcriptional, post-transcriptional and post-translational levels, presents a molecular mass of 65 kDa (Ibrahim et al, 2010).…”